1.The boy really doesn't know ______ next.
A.where to do B.what to do C.how to do D.how to do it
为什么选D不选B
在很多情况下,what to do=how to do it.我想这里选D而不选B是基于next.这个男孩应该是知道接下来该做什么,但是不知道怎么做.个人之见.
2.(Since) he mother was ill ,Mary had to look after her.
A.As B.When C.For D.Though
为什么选A
as:因为.for也可以做“因为”讲,但是语气很弱.