有关呕血与黑粪的叙述正确的是()
A、下消化道出血仅有黑粪
B、上消化道出血只有呕血
C、呕血一般不伴黑粪
D、出血量至少在5ml以上才会有黑粪
E、黑粪一定伴呕血
参考答案:A
In no country other than Britain, it has been said, ____ experience four seasons in the course of a single day.
A.people can
B.you can
C.can it
D.can one
薄膜电池存在S-W效应,S-W效应指的是()。