Question

动词用作主语时要加ing,但是过去式怎么加?

Answer 1

首先,Went本来就是go的过去式.只有动词才有这些变化.

其次,用表达动作的成分作主语,只能用动名词.所以应该说,

Going to U.S.is an precious experience.

但为强已发生,可用动名词的完成式.

Having gone to U.S.is an precious experience.