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【简答题】
设 x ， y ， z ∈R，且满足： x 2 ＋ y 2 ＋ z 2 ＝1， x ＋2 y ＋3 z ＝ ，则 x ＋ y ＋ z ＝________.
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【单选题】–May I go to the concert with you? – I’m afraid not ______you have a ticket, because I have only one.
A.
since
B.
if
C.
unless
D.
though
【简答题】如将变压器误接到等电压的直流电源上时,由于E= ,U= ,空载电流将 ,空载损耗将 。
【单选题】Many important leaders of different countries______ in the opening ceremony of the 29th Olympics held on August 8,2008.
A.
turned up
B.
turned down
C.
turned on
D.
turned over
【简答题】如将变压器误接到等电压的直流电源上时，由于空载电流将（），空载损耗将（）
【简答题】–May I have ____ ____? –My name is Jim White.
【单选题】–I _______ as the manager in this company. –May I know since when?
A.
worked
B.
had worked
C.
have worked
D.
am working
【单选题】用 LED 做 12V 电源指示,已知 LED 正向压降为 2.2V ,电流为 5mA 左右,则限流电阻应选 ( ) 为宜。
A.
200 Ω
B.
560 Ω
C.
1.8k Ω
D.
3.6K Ω
【单选题】– May I have an apple, Mum?--Certainly. But you ______ wash your hands first.
A.
may
B.
must
C.
can
D.
need
【单选题】–May I drink water? –Sorry, I don’t have__________.
A.
any; some
B.
some; any
C.
some; some
D.
any; any
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