当生活很艰难，你想要放弃的时候，请记住，生活充满了起起落落，如果没有低谷，那站在高处也失去了意义。When life gets hard and you want to give up, remember that life is full of ups and downs, and without the downs, the ups would mean nothing.我侧一步要躲闪的时候，瓶子打中了我的左髋部。As I side...
A species of cockroach sprays a substance , ethylacrolein, that is a kind of tear gas.某种蟑螂喷射一种催泪性毒气――乙 基丙烯 醛.It enables scientists to transfer genes between different species that would not interbreed in nature.它使科学家之间的转...