user: Teacher: Generate an appropriate single-sentence summary for the given text such that it includes the main topic of the text.
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By Marianna SpringSpecialist disinformation reporter, BBC News The adverts show the Democratic Party challenger with an earpiece, and say that he refused to have his ears checked for devices prior to the debate. The Biden campaign rejected the claims. The Trump campaign adverts ask: "Why won't Sleepy Joe commit to an ear test?" and "Who is in Joe's ear?" Accusations that presidential candidates have received debate help via hidden hearing devices are familiar, albeit unproven. Such allegations have been levelled against both Republican and Democratic candidates in the past. Prior to Tuesday's debate, the rumour about Mr Biden's supposed earpiece was circulating on several social networks, and was being promoted by the Trump campaign. At least 15 versions The advertising campaign was launched after the debate, and also promotes two other baseless but widely shared rumours about Mr Biden. One suggested he asked for breaks during the debate, and another accused him of refusing a "drug test". The photo featured in the advert is not from Tuesday's debate. It was first shared online in September 2019. In a number of the adverts, it has been doctored to show Mr Biden wearing wireless Apple headphones. This was not the case in the original image. Some versions circle the ear featuring the headphone. By Wednesday evening, there were at least 15 different versions of the advert, and according to Facebook's Ad Library, they had reached at least 10 million users. Facebook has pledged to label posts containing voting misinformation and point users towards accurate information ahead of the election. However its policy does not involve fact-checking political speech, including in advertisements. The company declined to comment about the latest Trump ad campaign. Rumour origins Hours before the debate, the claims went viral on Facebook and YouTube. Identical memes were pushed by a number of popular Facebook pages with names such as US Conservative and Unhinged Left. They claimed "Joe Biden should be inspected for a hidden earpiece as well as submit to a drug test before the debate". These memes are subject to fact-checks - and some have had warning labels applied to them on Facebook. The claims were picked up by Fox News and other conservative news outlets. They were further amplified by supporters of QAnon, an unfounded a conspiracy theory that claims President Trump is fighting a secret war against elite Satan-worshipping paedophiles. Those who believe in QAnon are known for promoting political disinformation on social media which targets opponents of the president. They shared close-up pictures of Mr Biden's ears, alleging a listening device was visible. During the debate, some also shared photos of a fold in Mr Biden's shirt, claiming it was caused by a wire, and of a supposed device on his wrist, where he wears a rosary in memory of his late son Beau. Nothing new Conspiracy theories about secret listening devices have been recycled in presidential election campaigns for the past two decades. Democratic candidate Hillary Clinton faced similar unfounded claims ahead of the 2016 presidential election. In 2004, rumours circulated among left-wing sites and blogs that President George W Bush was being aided by a secret earpiece. None of those allegations were found to be true. Even if a candidate did wear an earpiece, any advantage would be questionable. As TV and radio presenters can attest, listening to someone while simultaneously talking during the back-and-forth of a live event is a difficult skill to master.
Solution: US President Donald Trump's re-election campaign is running hundreds of Facebook advertisements pushing an unfounded conspiracy theory that Joe Biden cheated during the first US presidential debate.
Reason: This is a relevant summary for the given paragraph. It also contains explicit phrases from the given text

Now, solve this instance: Simon JackBusiness editor@BBCSimonJackon Twitter Prime Minister Theresa May has promised measures against Moscow if there is no adequate explanation for the poisoning. But she would be pushing against interests that touch UK football, members of the House of Lords, and valuable assets owned by UK companies. Those assets include BP's 20% stake in Russian oil and gas giant Rosneft. That's worth repeating - a FTSE 100 company owns a fifth of Russia's most valuable company, which is state controlled. BP's chief executive Bob Dudley sits on a board that is chaired by close Putin-associate Igor Sechin. So far, the two companies have managed to find a way to carry on business despite sanctions imposed after Russia's annexation of Crimea. Mr Dudley often has to leave the room during board meetings when matters pertaining personally to Mr Sechin arise as he is on a list of sanctioned persons. If sanctions get tougher - how will BP manage an asset that provides a third of its global oil production? So far the stock market has not moved to apply a discount to BP's holding, and sources close to the company have said they hope that any sanctions would target individuals rather than important foreign assets. But if the gloves really come off, what action would Russia take? A former executive of a telecoms company with a Russian subsidiary told me just how difficult Russia can make life. After the invasion of Crimea, Russia told the company to change all the phone numbers in Crimea to give them a Russian rather than Ukrainian prefix. Failure to do so would result in their licence to operate being suspended. The London Stock Exchange recently accepted a listing from EN+, a metals company controlled by Oleg Deripaska, who you may remember was courted by both Lord Mandelson and former Chancellor George Osborne aboard his yacht. Now Mr Deripaska is not on the sanctioned persons list but - as I reported in November last year - the proceeds of the London share sale were used to pay down his debt to sanctioned Russian bank VTB. The ties go deeper. Greg (Lord) Barker, former Energy Minister under David Cameron, is the non-executive chairman of EN+. There is nothing illegal or sanctions-busting in that, but it serves an illustrative tip of the iceberg of the huge amounts of work that UK advisers, lawyers and bankers derive from advising Russian customers located here and in Russia. Property deals Messrs Usmanov and Abramovich have taken a chunk of the hallowed turf of the Emirates (Arsenal) and Stamford Bridge (Chelsea) and have operated perfectly legally here. But both are on good terms with Vladimir Putin. If the way to hurt Putin is to hurt his friends, how far is the UK prepared to go? Is it ready to send a message that Russian money and business is not welcome in the UK just as Brexit looms. After expelling diplomats, one way for the UK to retaliate is to target Russian's huge UK property holdings. The Criminal Finance Act could be used to look more deeply into how the money used to buy premium London property was acquired. It is unlikely there will be widespread sympathy for the estate agents who make their money flogging penthouses to oligarchs, but Russian business has become an important fact of UK public life and the government may find it hard to target any new sanctions precisely enough not to deter valuable, legal business. There are other options - such as boycotting football's World Cup - but how many other countries would follow suit? Europe is also much more dependent on supplies of Russian gas than the UK. With Donald Trump pursuing a protectionist trade policy and with his hands full in North Korea, Theresa May's biggest test may be the amount of international support she can command.
Student:

assistant: A crackdown on Russia's UK business ties in the wake of the spy poison revelations will hit a complex and lucrative web of interests.