题目内容：

They can't decide _____ next.
A.What should do
B.how to do
C.what to do
D.what should they do

优质解答

选C.
句子意思：
他们尚未决定接下来该做什么.
句型转换：
They can't decide 【what to do】next 【疑问词+不定式】
=They can't decide 【what they should do】next 【宾语从句,陈述语序】
祝你开心如意!