______,please correct my mistakes in the composition.
| A．If so | B．If possibly | C．If not | D．If any |
____ he came back home that we knew what had happened .
| A．When it was | B．It was when | C．Was it when | D．When was it |
It was the training _____ he had as a young man _____ made him such a good engineer.
| A．what ; that | B．that ; what | C．that ; which | D．which : that |
It was _____ he said _____ disappointed me at that time.
| A．what ; that | B．that ; that | C．what ; what | D．that ; what |
It was not until late in the evening _____ her husband arrived home .
| A．which | B．when | C．that | D．how |
.—___________that he managed to get the information?
—Oh, a friend of his helped him.
| A．Where was it | B．What was it | C．How was it | D．Why was it |