Not until a monkey is several years old________ to exhibit signs of independence from its mother.
问题描述：
Not until a monkey is several years old________ to exhibit signs of independence from its mother.
A：before it begins
B：it does begin
C：does it begin
D：does begin it
答
C
not until位于句首的复合句,从句用正常语序,主句用倒装.