单项选择题
It seems oil（）from this pipe for some time. We'll have to take machine apart to put it right.
A．had leaked B．is leaking C．leaked D．has been leaking
单项选择题 （）he was a regular customer, the boss allowed 10% discount off the prices of the goods.
单项选择题 The course normally attracts 20 students per year,（）up to half will be from overseas.
单项选择题 You（）yourself about money.
