Question

请教2道英语选择题 请给出正确答案并讲解 谢谢

1 （），it immediately ran away.
a.Observing her b.On being oberved c.Having been oberved d.On her being oberverd

2 The experts were now fully convinced that the animal ( ) a puma.
a.must be b.should have been c.can only be d.could only have been

Answer 1

1.B On ... 和 when ... ,意思都一样，“当……的时候”。 On being observed也可以写作On the time when it is being observed 句意：一被人看到，美洲狮就跑掉了。
2.D 情态动词表达推测的语意概念时，对于过去事实推测一定要用于情态动词have以及过去分词形式进行搭配。 A 项 must be 是对客观现实的一种推测，应该跟主句的谓语动词“were now fully convinced ”保持一致，C项的can 与前面 的时态不一致，需改为could；B项should have been 表示本该是，而实际上不是的意思。因此答案为D。

Answer 2

第一题选D，on one’s being done表示一。。。就。。。
第二题选A，这里的must表猜测

Answer 3

1.b ，一…就 2 a,从concince可看出专家很确定，所以选第一个

Answer 4

1 b 2 a

Answer 5

1 D2.A

Answer 6

c和a