When the man came in, gun in hand, we all stood there, ________.
| A．frightened | B．frightening |
| C．being frightened | D．having frightened |
It is every citizen's duty to _____ our country when she is attacked by the enemy．
| A．approach | B．defend | C．support | D．preserve |
—How long have you been here?
—___ the end of last year．
| A．Since | B．At | C．By | D．In |
It rained for several weeks, completely ____ our holiday．
| A．ruined | B．ruining | C．to ruin | D．ruin |
Xiamen Xiang'an Tunnel, _____ is the first undersea tunnel built in mainland China, opened to traffic on April 26th．
| A．that | B．what | C．where | D．which |
A survey of the opinions of experts ____ that drinking a glass of hot milk before going to bed helps one sleep well．
| A．shows | B．show | C．is showing | D．have shown |