【简答题】In this article the author relies chiefly on ______to support his main arguments.
【单选题】The author begins his article with ______.
A.
an anecdote about his grandparents
B.
a quotation from his grandparents
C.
a description of, and a comment on, his grandparents' principle of life
D.
his admiration at his grandparents' way of life
【单选题】如图所示 , 理想变压器原线圈输入电压 u=U m sin ωt , 副线圈电路中 R 0 为定值电阻 , R 是滑动变阻器。 V 1 和 V 2 是理想交流电压表 , 示数分别用 U 1 和 U 2 表示 ; A 1 和 A 2 是理想交流电流表 , 示数分别用 I 1 和 I 2 表示。下列说法正确的是 ( ) 。
C.
滑片 P 向下滑动过程中 , U 2 不变 , I 1 变大
D.
滑片 P 向下滑动过程中 , U 2 变小 , I 1 变小
【简答题】如图1.3.32所示电路中,电阻R L 可调。试求R L 为何值时能获得最大功率P max ,并求此最大功率的值。
【简答题】《机械制图习题集》第二版 田凌 许纪旻 清华大学出版社 p29:3-3-2-10,P32:学号为单号的做1.3.5,学号为双号的做2.4.6 P29:第10题 P32:第1题 P32:第2题 P32:第3题 P32:第4题 P32:第5题 P32:第6题
【单选题】The author mentioned 'Yankee' in his article was to ______.
A.
show his hatred towards westerners
B.
give a vivid image of tall tales to us
D.
illustrate the characteristic of tall tales
【单选题】The author begins his article with ______________________.
A.
an anecdote about his grandparents
B.
a quotation from his grandparents
C.
a description of, and a comment on, his grandparents' principle of life
D.
his admiration of his grandparents' way of life.
【简答题】在下图 所示桥式整流电路中,已知变压器二次绕组电压 U 2 =100V , R L =3k Ω,交流电源频率为 50Hz ,若忽略二极管的正向电压和反向电流。试求: ( 1 ) R L 两端电压的平均值 U O ; ( 2 )流过 R L 电流的平均值 I O ; ( 3 )流过二极管的电流 I D 及二极管承受的最高反向电压 U RM 。