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【简答题】
数字通信系统与模拟通信系统相比,其主要优点有哪些?
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举一反三
【单选题】He has some trouble ____ his classmates but he has no trouble ____ doing his lessons. [ ]
A.
with; with
B.
with; in
C.
in; in
D.
in; with
【单选题】―What your English teacher doing now? ―He _____ a newspaper.
A.
is, reading
B.
is, is looking at
C.
does, watching
D.
is… is reading
【简答题】A．He is doing research. B．He works long hours in the lab. C．He is progress. D．He was unhappy until recently.
【单选题】He __________ some cooking at that time, so ___________me.
A.
did, heard
B.
was doing, heard
C.
was doing, didn’t hear
D.
did, didn’t hear
【单选题】He has some trouble ______ his classmates, but he has no trouble ______ doing his lessons.
A.
with; with
B.
in; in
C.
with; in
D.
in; with
【单选题】—What were you doing when she dropped in? —I for a while and_________ some reading.
A.
was playing; was going to do
B.
played; did
C.
had played; was going to do
D.
had played; did
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