3 . Some sounds cannot________ by the human ear.
有些声音是人的耳朵无法察觉到的。

4 . Under the________ conditions many children are going hungry.
在目前情况下，会有很多儿童忍饥挨饿。

5 . ________, I could have tried harder but I still don’t think all this criticism is fair.
不可否认，我本来可以再努力些。尽管如此，我认为这些批评也并非完全公道。

6 . This drug can be safely used in_________with other medicines.
这药可以与其他药物一起安全服用。

7 . I think he ________ quite a lot when his wife left him.
我想他妻子离开他时，他一定很痛苦。

8 . Mary Shelley was just 18 when she wrote the horror________ ‘Frankenstein’. 
玛丽·雪莱 创作《科学怪人》这部恐怖小说名作时年仅 18 岁。

9 . Energy ________ reduces your fuel bills and helps the environment.
节省能源能减少你的燃油费，而且还有利于环境。