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.
