—Why does the lake smell terrible?
—Because large quantities of water_____.
| A．have polluted | B．is being polluted |
| C．have been polluted | D．has been polluted |
Our teacher’s plans are still ____________.
| A．attentive | B．tentative | C．attend | D．tent |
In our school, the students have three__________ courses and seven __________courses.
| A．required ;alternative | B．require ;alternative |
| C．requiring ; alternative | D．reqiure;alternative |
Being able to speak another language fluently could be a great ___when you are looking for a job.
| A．advantage | B．chance | C．help | D．importance |
It doesn’t often snow in my hometown in winter, but it ___be rather cold sometimes.
| A．shall | B．should | C．can | D．would |
His first baby was born soon after he got married, which seemed to have ___his sense of responsibility.
| A．brought down | B．brought out | C．turned down | D．turned out |