Great amounts of water            poured into the river from the factories two years ago.

was

were

has been

have been

考查时态和主谓一致。句意：两年前，工厂将大量废水排入河中。根据two years ago 可知，句子使用一般过去时。....amounts of修饰不可数名词作主语时，谓语动词用复数形式，即谓语动词与amounts保持数的一致。故选B项。

Small sailboats can easily turn over in the water ________.

if not managed carefully

if are not managed carefully

unless not managed carefully

unless are not managed carefully

--- So you missed the meeting.

---           .I got there five minutes before it finished.

Not at all

Not exactly

Not especially

Not really

考查情景交际用语。句意：---你错过了开会。---我在会议结束前五分钟到达会场。可以看出答话者认为对方讲话不够确切。A. Not at all一点也不；不客气；B. Not exactly不确切   C.Not especially不是特别 D.Not really不是真的。故选B项。