3個英文文法問題!!!急!!!

1))There is no obvious winter in Taiwan,with temperatures rarely dropping very low and snow 【seen】 only on the high mountains. 2))There is no obvious winter in Taiwan,because temperatures rarely drop very low and snow 【is】 seen only on the high mountains. Q:為何第1句要用 seen 呢? 第2句為何多了個be動詞? 意思跟第1句一樣嗎? 3))I... show more 1))There is no obvious winter in Taiwan,with temperatures rarely dropping very low and snow 【seen】 only on the high mountains.

2))There is no obvious winter in Taiwan,because temperatures rarely drop very low and snow 【is】 seen only on the high mountains.

Q:為何第1句要用 seen 呢?
第2句為何多了個be動詞? 意思跟第1句一樣嗎?

3))I wish it 【could】 go on forever.

假設法:I wish (that) S+V

Q:為何要用 could 而不用 can?
2 answers 2