利用链接
胡佛水坝:有趣的旅游景点
1．I do it every day.（我每天做这样的事。）2．I did it yesterday.（昨天我做了这件事。）
3．I shall/will do it tomorrow.（明天我要做这件事。）4．I am doing it now.（现在我正在做这件事。）
5．I was doing it at that time.（当时我正在做这件事。）
6．I shall/will be doing it at 9：00 tomorrow morning.（明天早晨九时我会正在做这件事。）
7．I have done it already.（我已把这件事做好了。）
8．I have done it before I went home yesterday.（昨天我在回家之前就把那件工作做完了。）
9．I shall/will have done it before you come back tomorrow.（明天在我回来之前我会把这件工作做好。）
10．I have been doing it for two days.（这件工作我已做了两天了。──说话时工作尚未做完，所以还得继续做。）
11．I had been doing the work for two hours when the teacher came.
（老师来时那件工作我已做了两小时了。──当时工作尚未完成，所以老师来了我还继续在做。）
12．I shall/will have been doing it for an hour when you come to see me at 9：00 tomorrow morning.
（明天早上九时你来看我时，我会在做那件工作做了一小时。──当然尚未能做完，还得继续做下去。）
1．I do it every day.（我每天做这样的事。）2．I did it yesterday.（昨天我做了这件事。）
3．I shall/will do it tomorrow.（明天我要做这件事。）4．I am doing it now.（现在我正在做这件事。）
5．I was doing it at that time.（当时我正在做这件事。）
6．I shall/will be doing it at 9：00 tomorrow morning.（明天早晨九时我会正在做这件事。）
7．I have done it already.（我已把这件事做好了。）
8．I have done it before I went home yesterday.（昨天我在回家之前就把那件工作做完了。）
9．I shall/will have done it before you come back tomorrow.（明天在我回来之前我会把这件工作做好。）
10．I have been doing it for two days.（这件工作我已做了两天了。──说话时工作尚未做完，所以还得继续做。）
11．I had been doing the work for two hours when the teacher came.
（老师来时那件工作我已做了两小时了。──当时工作尚未完成，所以老师来了我还继续在做。）
12．I shall/will have been doing it for an hour when you come to see me at 9：00 tomorrow morning.
（明天早上九时你来看我时，我会在做那件工作做了一小时。──当然尚未能做完，还得继续做下去。）
