标明下列句子成分 1 There is nothing to do but do some reading.2 It's

1 There(引导词) is （谓语）nothing （主语）to do （定语）but do some reading（从but到最后是插入语）
2 It（形式主语）is （谓语） cruel（表语） of you（逻辑主语） to kill the cat.（真正主语）
3 They（主语） are （谓语）accustomed （表语）to（介词） not talking at meals .（介词宾语）
4 The noise （主语）of desks being opened and closed （定语,修饰the noise）can be heard (谓语)out in the street（地点状语）

2.to kill the cat.是真正的主语。It是形式主语这是主系表结构。
4，还有情态动词的被动语态The noise of desks being opened and closed是主语can be heard out 是谓语