问题补充:
It was only after World War II had drawn to a close in the United States.
A. did the baby boom begin
B. that the baby boom began
C. when the baby boom began
D. then the baby boom began
答案:
A. did the baby boom begin
(答案→)B. that the baby boom began
C. when the baby boom began
D. then the baby boom began
解析::考查强调句型。本题考查强调句型:it is/was被强调成分that/who…;强调句型的最大特点是把it is/was…that/who…去掉句子仍然成立。本题强调的是主语only after World War II had drawn to a close句意:只有在第二次世界大战结束后,美国人口出生快速增才开始。故B正确。