In this task, you are given two sentences in the English language (Sentence 1 and Sentence 2). Your task is to identify the connecting word between the two sentences.

Example Input: Sentence 1:In later conflicts , the United States Army used black soldiers in the Spanish -- American War and in World War I . Sentence 2:However , when the United States Army Air Service was formed , only white people were allowed .
Example Output: however

Example Input: Sentence 1:AFIS is not internationally regulated like Air traffic control is by ICAO . Sentence 2:However Eurocontrol have issued a recommendation called Eurocontrol manual for AFIS .
Example Output: however

Example Input: Sentence 1:Molecular biomarkers are often used in early drug development studies . Sentence 2:For instance , they are used in phase I study for establishing doses and dosing regimen for future phase II studies .
Example Output:
for instance