1. — 你曾去过大连吗?
    — Have you ______ ______ to Dalian?
    — 是的,去过.那是一个美丽的城市.
    — Yes, I ______. It's a beautiful city.
2. 我看过很多次英文电影了.
    I ______ ______ English films many times. 
3. 你曾听说过外星人吗?
    ______ you ______ ______ ______ the aliens?
4. 水族馆里有如此多的不同种类的鱼.
    There are ______ ______ different kinds of fishes in the aquarium.
5. 他们两人都不擅长运动.
    ______ ______ them is good at sports.