Some researches have proved that water quality ____ due to too many dams and pumps in some areas.
| A．has been declined | B．is being declined |
| C．is declining | D．had been declining |
You’d better take into account your own________and weaknesses before choosing a major.
| A．strengths | B．benefits |
| C．dislikes | D．favorites |
—Is the letter from your mother?
—Yes.But she ________the letter herself，because she doesn’t even know one word.
| A．needn’t have written | B．can’t have written |
| C．might not have written | D．should not have written |
________he referred to in his article was often discussed by many people in the past.
| A．That | B．What |
| C．Whether | D．Where |
Social practice is an opportunity for students to gain________better understanding of how________society operates.
| A．the；the | B．the；/ |
| C．a；/ | D．the；a |
—I can’t thank you enough for the gift you sent me for my birthday the other day.
—________.
| A．That’s right | B．Don’t mention it |
| C．With pleasure | D．Nice work |