_____ work has been done to prevent the river being polluted.
A .A number of B A mass of C Several D. A good many
Mr. White will come to the party on Sunday, _______ he promised to every one of us.
| A．when | B．that | C．what | D．which |
Mary has recently got engaged ________ a foreign teacher, who has been engaged ________ education research for years.
| A．with; in | B．to; in | C．in; to | D．in; for |
Time ________ quickly. Three years passed before we knew it.
| A．went by | B．went on | C．went away | D．went off |
Mr. Smith is busy these days ________ a new book on how to develop a child’s reading skill.
| A．working out | B．working on | C．working for | D．working with |
It makes no ________ to me what she says. I won’t care.
| A．choice | B．efforts | C．difference | D．differences |