【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】His article concerning population control was published in the ( ) issue of China Daily.
【简答题】In this article the author uses ______ to support many of his important points in the news story.
【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.
【单选题】The author begins his article with _____.
A.
a specific example from his own experience
B.
a specific example based on a story he heard
C.
a summary of his main argument
【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 。