【单选题】– How long have you been collecting stamps? – Ever ______ I was twelve. I have been collecting stamps for about eight years.
【简答题】I have been working for months to ______ a way of solving this problem,but as yet I have not been successful. 我已经工作了几个月想找出解决问题的方法,但是到目前为止还没有成功。
【单选题】电路如下图(a)所示,输入电压u1的波形如下图(b)所示,试问指示灯HL的亮暗情况为()。
【简答题】At that moment, with the crowed watching me, I was not afraid in the ordinary sense, as I __if I___alone. Awould have been...had been Bshould be...had been Ccould be ...were Dmight have been...were
【单选题】Now I get the telegram I _______.
【单选题】_______ your advice, I would have been caught in the traffic and I wouldn't have been there on time. [ ]
【单选题】______more time, I might have been abroad to spend my holiday.
【判断题】I would have told him the answer had it been possible, but I have been so busy then.()
【单选题】---How long have you been studying at this school? --- I have been studying here____.
A.
since I was thirteen years old
C.
at the age of thirteen
【简答题】下图(a)所示是一个反相输入的加法器电路。已知R 11 =R 12 =R f 。如果u i1 ,u i2 的波形如图(b)所示,试画出输出电压u o 的波形。