He was observed ________ into the house before the owner came back.
| A．to slip |
| B．slip |
| C．slipping |
| D．slipped |
The most important thing about cotton in history is _____ part that it played in _____ Industrial Revolution.
| A．不填；不填 | B．the；不填 | C．the; the | D．a; the |
—What do you think of the manager of your company?
—Oh, he is ________ manager who’s pleasant to work with.
It’s ________ pleasure to work with him.
| A．the; a | B．a; a | C．a; the | D．不填; a |
Apples are usually sold by ________ weight and eggs are sometimes sold by ________ dozen.
| A．the; the | B．/;a | C．/; the | D．the; a |
—What about ____ book?
—It’s too difficult ____ book for beginners.
| A．the; the | B．a; a | C．a; the | D．the; a |
Whenever you are in trouble ,don’t hesitate _____us for help.
| A．in asking | B．with asking | C．to ask | D．to asking |