择题When did you decide to be a teacher? Let me see.I am thirty,and I have wanted to be one since_

d I was twenty 从宏观上来看就是一个时间点,而连词since的后面就要求加时间点,故正确.您好！since+一段时间+ago也是可以用于完成时的。since不可以+一段时间但since的后面接ago 是可以用时间点的如 They have lived in that house since two years ago.给个例句如何？如 They have lived in that house since two years ago.没错。这个 two years ago是指发生动作lived的第一天，从宏观上来说，它是实质仍然是一个时间点了。明白了。非常感谢您！我在学新二。语法强化上的题。请问如何与您联系请教？