The driver carefully checked his car （） it should go wrong on the way.

单项选择题Only after a baby seal is pushed into the sea by its mother （） to swim.

A. how will it learn
B. will it learn how
C. it will learn how
D. and it learns how

单项选择题（） his second heart attack if he hadn’t smoked He might not have.

A. Would he have had
B. Would he have
C. Had he had
D. Were he to have