Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
It was not long until Apple released their first portable computer, the Macintosh Portable in 1989. Although due to considerable design issues, it was soon replaced in 1991 with the first of the PowerBook line: the PowerBook 100, a miniaturized portable; the 16 MHz 68030 PowerBook 140; and the 25 MHz 68030 PowerBook 170. They were the first portable computers with the keyboard behind a palm rest and a built-in pointing device (a trackball) in front of the keyboard. The 1993 PowerBook 165c was Apple's first portable computer to feature a color screen, displaying 256 colors with 640 x 400-pixel resolution. The second generation of PowerBooks, the 68040-equipped 500 series, introduced trackpads, integrated stereo speakers, and built-in Ethernet to the laptop form factor in 1994.
What replaced the Macintosh Portable in 1991?
A: the PowerBook line

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Sleep involves great changes in brain activity. Until the 1950s it was generally believed that the brain essentially shuts off during sleep, but this is now known to be far from true; activity continues, but patterns become very different. There are two types of sleep: REM sleep (with dreaming) and NREM (non-REM, usually without dreaming) sleep, which repeat in slightly varying patterns throughout a sleep episode. Three broad types of distinct brain activity patterns can be measured: REM, light NREM and deep NREM. During deep NREM sleep, also called slow wave sleep, activity in the cortex takes the form of large synchronized waves, whereas in the waking state it is noisy and desynchronized. Levels of the neurotransmitters norepinephrine and serotonin drop during slow wave sleep, and fall almost to zero during REM sleep; levels of acetylcholine show the reverse pattern.
The three types of brain activity that can be measured are what?
A: REM, light NREM and deep NREM

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The changes included a new corporate color palette, small modifications to the GE logo, a new customized font (GE Inspira) and a new slogan, "Imagination at work", composed by David Lucas, to replace the slogan "We Bring Good Things to Life" used since 1979. The standard requires many headlines to be lowercased and adds visual "white space" to documents and advertising. The changes were designed by Wolff Olins and are used on GE's marketing, literature and website. In 2014, a second typeface family was introduced: GE Sans and Serif by Bold Monday created under art direction by Wolff Olins.
Who composed the slogan, "We Bring Good Things to Life"?
A: unanswerable

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Small, cheap discoidal ceramic capacitors have existed since the 1930s, and remain in widespread use. Since the 1980s, surface mount packages for capacitors have been widely used. These packages are extremely small and lack connecting leads, allowing them to be soldered directly onto the surface of printed circuit boards. Surface mount components avoid undesirable high-frequency effects due to the leads and simplify automated assembly, although manual handling is made difficult due to their small size.
What has been in use since the 1990s?
A:
unanswerable