The argument remains extremely heated    there are necessary conditions of existence such as water on the Mars.
#71649
A
that
B
whether
C
if
D
which
推荐题目
It was ______ten o’clock ______he returned home.
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A
\ …when
B
at …when
C
at …that
D
\...that
I want to know ______the thief was caught on the spot.
#73997
A
which
B
that
C
what
D
whether
The engineer ______my father works is about 50 years old. 
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A
to whom
B
on whom
C
with which
D
with whom
The professor said he could talk on _____ interested the audience.
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A
any topic
B
which topic
C
whichever topic
D
the topic he thought it