1.When was the first man made satellite sent(send) up into space?(此句用過(guò)去時(shí),發(fā)射衛(wèi)星已經(jīng)發(fā)生,所以用過(guò)去時(shí)）
2.She helped(help) him with his homework yesterday.（此句也用過(guò)去時(shí),有過(guò)去時(shí)間yesterday做標(biāo)志）
3.John was heared(hear) to go upstairs two hours ago.（此句用被動(dòng)語(yǔ)態(tài),John是被聽到,而且也有過(guò)去時(shí)間 two hours ago 做標(biāo)志,所以要用過(guò)去時(shí)）
4.Is paper made(make) of wood?此句要用被動(dòng)語(yǔ)態(tài),紙是以木頭為材料制成的,紙是被制造.