When he was a boy, he used to go there and watch _____.
| A．to repair bicycles |
| B．bicycles to be repaired |
| C．bicycles being repaired |
| D．repairing bicycles |
20．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 |
19．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 |
18．Everyone must have known the death of the waitress, __________?
| A．must they | B．mustn’t they | C．haven’t they | D．have they |
17．---Tony is such a selfish person.
---I agree. Never again________with him.
| A．I will deal | B．I do deal | C．will I deal | D．do I deal |
16．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 |