1.It isn’t quite _____ ______ he will be present at the meeting.
A.sure; whether
B.sure; if
C.certain; whether
D.certain; that
C 为什么ABD不可以选?
15.He treated all the people around him,______he knew or he didn't know,______.
A.if,friendly
B.whether,friendly?
C.if,in a friendly way
D.whether,in a friendly way
D 一样的疑惑,为什么其他不可以选?