下列各句中，没有语病的一句是

I don’t know___next.Let’s ask our teacher for help.

Some Chinese students find it difficult to understand native speakers when in London.—Exactly, ______ they’ve learned a lot about grammar and known many words

.Most business letters and government reports are the main situations _________ formal language is used. ^*

下列句子不是宾语前置的一项是（ ）