________ is very important in doing any scientific work.
| A．Album | B．Category | C．Accuracy | D．Assume |
We ____ last night, but we went to the concert instead.
| A．must have studied | B．might study | C．should have studied | D．would study |
_____with this challenge, he should meet it without any hesitation.
| A．Facing | B．Having faced | C．Being faced | D．Faced |
Only when we are abroad ____feel how important English is.
| A．we will | B．do we | C．will we | D．are we |
He has known the truth. Therefore, there is no ____ to keep it a secret
| A．chance | B．doubt | C．possible | D．likely |
In China, a good many traditional customs have____.
| A．died down | B．died off | C．died away | D．died out |