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【单选题】
下列关于力的投影和分力的关系,说法正确的是( )。A.
在直角坐标系中,分力的大小和对应坐标轴上投影的绝对值是相同的。
B.
分力是矢量,有大小有方向
C.
投影是代数量,有大小有正负
D.
以上都对
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【单选题】Travelling in space has been made __________ possible with the development of science and technology.
A.
that
B.
/
C.
it
D.
this
【单选题】A lot of countries have gained excellent achievements in space technology, China, _____. [ ]
A.
such as
B.
for example
C.
namely
D.
that is
【单选题】The space shuttle program entails the use of sophisticated technology.
A.
enhances
B.
develops
C.
creates
D.
involves
【单选题】A lot of countries have gained excellent achievements in space technology,China, _______. [ ]
A.
such as
B.
for example
C.
namely
D.
and so on
【单选题】If China’s space technology has achieved ____ breakthrough in this field, it really is ____ amazing wonder.
A.
the; an
B.
a; an
C.
不填; the
D.
a; 不填
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