流体流动综合实验中用差压变送器测量压差,请简述差压变送器工作原理?
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1) Which do you prefer to keep in touch with your friends. QQ _________ WeChat?
A. and
B. but
C. or
D. so
-Which do you like better,apple_______ orange?-I don't like apple _______ orange. I like watermelon.
A. and; or
B. and;but
C. or;but
D. or;or
Cross the road carefully. Look both ways , ______ you might be knock down .
A. and
B. but
C. or
D. so
Put on your coat and go with me ,_______ you will be left alone at home .
A. and
B. but
C. or
D. so