根据下列句子及所给汉语注释，写出空缺处各单词的正确形式。每空只写一词。
The exercises are designed to ________ (增强) your stomach muscle.
Don’t be frightened by the television camera. Just speak        (自然地).
The boy spoke in a low voice       （承认）that it was his fault.
Are you well __________(准备) for the entrance examination?
As the storm drew near, black clouds were __________ (聚集) over the sky.
However, his __________ (知识) of French remained very weak.
     (令人吃惊的是) , some graduates with qualification failed to find jobs.
The Bank of China has a lot of __________ (支行) in the world.
This kind of tree can only grow in the __________ (北方) parts of China. 
Nuclear physics is ________（超出） my understanding.