滑滑板时带护肘和护膝是必要的.Elbow pads and knee pads are essential on a skateboard.所有参赛者比赛时都必须佩带安全头盔及护膝、肘等可能必要的安全护具.It is mandatory that riders wear and approved safety helmet during racing.我要一副护腕和两副护膝.I want a pair of wrist protecto...
Under the optimum condition the yield of isopropyl cyclopropane carboxylate is 92 %.在最佳反应条件下,环丙烷羧酸异丙酯的产率达92%.Isopropyl p - hydroxybenzoate was synthesized with toluene - p - sulfonic acid as catalyst.以对 甲苯 磺酸为催化剂合成了尼泊金异丙...
People were booing and throwing things at them.人们向他们喝倒彩、掷东西。You can hear the crowd booing.你可以听到人群中的一片呸呸声.She kept her dignity despite the booing.尽管嘘声四起,她依旧泰然自若....