若用pHs表示碳酸钙饱和溶液的pH值,则当()时可判定循环水稳定、不结垢。
A、pH=pHs;
B、pH<pHs;
C、pH>pHs
;D、pH=pHs=0。
参考答案:B
John and his sister went on holiday with a cousin of _____. [ ]
A. his
B. her
C. their
D. theirs
幽门螺杆菌含有丰富的()
A.蛋白酶
B.尿素酶
C.脂肪酶
D.淀粉酶
E.以上都是