I think english is fan变过去式

I think English is . I think English is---Fench I think english is important 改成疑问句和否定句怎么变? I think English is _____ math.--Yes,I think so. I think there is___with my kitchen fan I think learning English is us I think is good for our english i think she is ---at English real i think your english is rather English is very useful l ,I think i think your english foundation is ok. I think English is a ( ) language.(use)