Scientists are trying their best to_______ ways to treat the terrible disease caused by Ebola(埃博拉).
Mike is studying in _______ university and he wants to be _______ engineer .
--- How did you find your visit to Dalian, Joan? --- ________.
Mike would rather ________emails to friends while John prefers________ phone calls.
Put it down, Kitty. You mustn’t read ________letter.
She has very________ close friends so that she really doesn’t know________.