Question

It was not until ________ that ________ to prepare his lessons．

1. A.
   did his father come in; the boy began
2. B.
   his father came in; the boy began
3. C.
   did his father come in; did the boy begin
4. D.
   his father came in; did the boy begin

Answer 1

B
本题是强调句，被强调部分是由until引导的时间状语从句，应该用陈述语序，故选择B或D．that后面是主句，也应用陈述语序，所以答案为B．not是否定主句的，但在强调句中，通常和until一起连用．