现在进行时: Look!The dinosaur is falling down . 一般过去时: The dinosaur fell down last night. 再问: 用(often) 改 Look!The dinosaur is falling down 此句~~ 再答: often 常用于一般现在时,应该这样改: The dinosaur often falls down. 再问: 那 Yesterday he did homework very carefuly 用(always)和(now)改写…… 再答: He always does his homework very carefully. He is doing his homework very carefully now.