12. ---Hi, Tom. Any idea where Jane is?
---She in the classroom. I saw her there just now.
| A．shall be | B．should have been | C．must be | D．might have been |
Helen devoted herself ________to her research and became a top scientist in the field of applied physics．
| A．seriously | B．extremely | C．entirely | D．strictly |
Vitamin D helps our bodies make a special chemical，and this special chemical, ______
affects our brains，making us feel happy．
| A．in turn | B．in particular | C．in advance | D．in short |
Everyone must have known the death of the waitress, __________?
| A．must they | B．mustn't they | C．haven't they | D．have they |
．一 Tony is such a selfish person．
一 I agree. Never again ________ with him.
| A．1 will deal | B．I do deal | C．will I deal | D．do I deal |
After driving for 20 miles，Jackson realized that he ________in the wrong direction．
| A．was driving | B．drove | C．had been driving | D．had driven |