When ____ help, one says "Thank you" while when _____ help, one asks "Can I help you?"
| A．ffered; offered | B．ffering; offered | C．offering; offering | D．offered; offering |
Without the 
air to hold some of the sun’s heat, the earth at night ____ for us to live.
| A．would be freezing cold | B．will be freezing coldly |
| C．would be frozen cold | D．can freeze coldly |
It is hard for me to imagine what I would be doing today if I ____ in love, at the age of seven, with the Melinda Cox Library in my hometown.
| A．wouldn’t have fallen | B．had not fallen |
| C．should fall | D．were to fall |
“Do you know his address？” “No, I also wish I _____ where he _____.”
| A．knew, live | B．knew, lives |
| C．know, lives | D．know, lived |
“I still haven’t thanked Aunt Lucy for her present.” “It’s time you _____.”
| A．do | B．did | C．had | D．would |
______ smoking, he would not have got cancer in the lung.
| A．Was he given up | B．Had he given up |
| C．Did he give | D．If he gave up |