1.We had to stay at home because of the heavy rain.(because是连词,后面要跟句子,如果后面是名词或名词性词组,则用because of)
2.I find all these words are spelt wrong.(be动词+动词ing表示主动或正在进行,spell既不是这些words主动的去自己拼写也不是正在拼写,而是被拼写,所以应该用be动词+动词的过去分词表示被动)
3.Both of them come from America.(both of 加名词的复数做主语相当于复数,谓语动词用相应的复数)
4.She says English words are hard to remember.(这个地方用动词不定式做状语,表示目的或结果) P.S.如果我没看错的话,你的"English word"应该是"English words"吧,不然单数第三人称做主语谓语动词应该用单数,是is不是are啊