【单选题】按《安规》规定,作业人员应对安规每年考试()次。
【简答题】试求下列函数的拉氏变换. (1)f(at-b)u(af-b); (2)e-tu(t-1).
【单选题】车站技术管理和作业组织应在( )中规定。
【单选题】已知数列{a n }既是等差数列又是等比数列,则这个数列的前n项和为 [ ]
【简答题】You (stand)______ several feet away if you wish to get the full effect of the picture.
【单选题】Part 2 task1 Passage1, question2:
A.
Richard lent some money to Michael
B.
Michael helped Richard build his house
C.
Michael invited Richard to fly kites
D.
Richard set fire on Michael's house
【单选题】Part 2 task2 Conversation1, question1:
B.
Because she was not hungry
C.
Because her car was stolen
D.
Because she just had her lunch
【单选题】已 已知 f(t)=e at ,(a 为实数 ) ,则f(t)的积分的拉氏变换为
【单选题】已知数列{a n }的前n项和S n =q n -1(q∈R,q≠0),则数列{a n }( )