Now and then they would ______ our house and have a talk with us.
| A．call on | B．drop in at |
| C．drop in on | D．drop in |
After his company’s closing down , he lost both his wealth and confidence , and never found __________ of them again .
| A．both | B．neither |
| C．either | D．all |
We are really disappointed to see millions on earth who have nothing but hunger and cold __________ no chance to improve their life .
| A．to have | B．having |
| C．having had | D．have |
We are roommates for 3 years and never once __________ .
| A．we have quarreled | B．have we quarreled |
| C．do we quarrel | D．did we quarrel |
I will never forget the park __________ I spent so many happy hours there with my parents last summer .
| A．where | B．because |
| C．which | D．so |
In fact , the hazy weather problem is so severe now that it has aroused __________ nationwide concern about __________ environmental pollution .
| A．/ ; / | B．/ ; the |
| C．a ; / | D．a ; the |