_________ it takes many years to gain the skills of an expert.
| A．It is well known to us that | B．As is known to us that |
| C．As we know that | D．That is well known to us |
Hearing his words ,I couldn’t decide or remain .
| A．whether to go abroad | B．if I go abroad |
| C．if to go abroad | D．to go abroad |
Questions and exercises are given by the computer, which decides ______ to move the students ahead, review an easier level, ____ give more work on the same level.
| A．either, or | B．both, and . | C．whether, or | D．not only, but also |
—Will you go to Mary’s birthday party?
—No, ____ invited, I can’t go to it. I’ll be too busy then.
| A．if | B．unless | C．even though | D．when |
The librarian promised to get the book for me ____she could remember who last borrowed it.
| A．in case | B．if only | C．even if | D．ever since |
—What do you mean ______ saying “The boy is overgrowing”?
—I mean that he is tall ____ his age.
| A．as to, for | B．by, for | C．about, with | D．by, to |