—It's difficult for me ________ there are few new words in it.
如图所示,给试管里的水加热,水沸腾后,水蒸气推动活塞迅速冲出试管口,水蒸气在这个过程中( )
提到细菌,你会想到芽孢.下列关于芽孢的叙述错误的是( )