that is...(也就是说..) 后面可以加句子吗?

that is...(也就是说..) 后面可以加句子吗? that is to say是“也就是说”的意思吗?please? the professor knows three languages,( )english,french and japanese.A.that is B.which is这里的that is是“也就是说”的意思吗?那在句子中做什么成分?为什么不能选B呢?不好意思说错了 I noticed that he is very nervous 语法问题其中noticed 是过去时 也就是说主句是过去I noticed that he is very nervous 其中noticed 是过去时 也就是说主句是过去,但从句中用的是 is 为什么不用was呢 it is said that后加什么时态 it is hign time that 后用什么时态 it is no wonder 后用why还是that? It is reported that 后可以用过去完成时吗? It is +adj.+that后可以加祈使句吗? it is said that后加什么词 there is no doubt 后的that可省略吗 is that one over there后接什么代词 It is +adj.+that后可以加祈使句吗? l like music that后加is还是are. 那是我 that is 后用me还是i I have some trouble,that is I can't find him and he will be in danger.这里that is 我记得高中语法中有that is 做插入语的情况，但是好像that is后面紧跟着有一个逗号，也就是说，是以一个短句子形式的放在句 We much admire his working so hard.his working 后面为什么不加is?Domjin，也就是说如果要加is就必须这样写we much admire that his working is so hard. that is