Question

【題目】The waste water has been made clean before it goes into the river ________ the new rule was made.
A.when
B.ever since
C.after
D.before

Answer 1

【答案】B
【解析】句意：自從新規(guī)則被制定以來(lái)，在廢水進(jìn)入河流之前，就已經(jīng)被處理干凈了。when當(dāng)……時(shí)；ever since自從；after在……之后；before在……之前；主句中使用現(xiàn)在完成時(shí)，說(shuō)明應(yīng)該使用ever since引導(dǎo)這個(gè)時(shí)間狀語(yǔ)從句。故B正確。