【单选题】He was all wet when he got home because he _____ his umbrella in the underground. [ ]
【单选题】He took his umbrella with him lest it _____.
【简答题】设A=P(x,y,z)i+Q(x,y,z)j+R(x,y,z)k, r=xi+yj+zk. 求证dA=(grad P·dr)i+(grad Q·dr)j+(grad R·dr)k.
【单选题】已知 111 为二进制定点无符号整数,则其表示的十进制数为( )。
【简答题】阅读理解。 It was a beautiful sunny day. Miguel decided to go to the beach. He called his friends, but Mario was at work, and Rosa was at her grandmother's home. So he had to go to the beach alone. He took...
【简答题】Complete the sentences with but, because or so.(用but,because,或 so填空) He was tired 1 he took a nap. He was wet 2 he forgot his umbrella. The zoo was busy, 3 we still got to see the pandas. We'd better ...