1、这是的英语：This is，英 [s ?z] 美 [s ?z]。
2、这是新系统的一大弊端。This is the one major drawback of the new system。
3、这是英国同类学校中最早的一所。The school is the first of its kind in Britain。
4、氟化物可以强化生长中的牙齿，这是已证明的事实。It is a proven fact that fluoride strengthens growing teeth。
这是什么？
英文：what is this?／What is it?
Ho, ho! What have we here?
嗬嗬！这是什么？
And what, we may ask parenthetically, does it mean?
我们想顺带问一句，这是什么意思？
"What are you getting at now?" demanded Rick.
“你这是什么意思？”里克问道。
