刘斌同学为了减少蚯蚓在地面爬行时的阻力,为了便于观察其爬行的速度,特意给蚯蚓体表涂上了一层凡士林油,你认为蚯蚓将会( ) A.运动加快 B.死亡 C.身体不动 D.运动减慢 答案:B—Are you ________ that you can fix the bike ________?— Sure, I’m good at DIY.A. certain; yourselves B. certain; yourselfC. sure; yourselves D. uncertain; yourself