题型:填空题 We can be proud of ourselves, but we had better find out _____ we have got to be proud of. [ ]A. what is it thatB. that what it isC. what it is thatD. that what is it 查看答案
题型:填空题 摆式列车是集电脑、自动控制等高新技术于一体的新型高速列车,当它转弯时,在电脑控制下,车厢会自动倾斜,产生转弯需要的向心力;行走在直线时,车厢又恢复原状,靠摆式车体的先进性无需对线路等设施进行较大的改造,就可以实现高速行车。假设有一摆式超高速列车在水平面内行驶,以216km/h的速度拐弯,拐弯半径为1.8km,为了避免车厢内的物件、行李测滑行和站着的乘客失去平衡而跌倒,在拐弯过程中车厢自动倾斜,车厢底部与水平面的倾角的正切约为多少?(g=10 m/s2) 查看答案