骨骼肌兴奋—收缩耦联中起关键作用的离子是
A.Na+
B.K+
C.Ca2+
D.Ma2+
E.Cl-
参考答案:C
There are many idioms used in English _____ quite a few of them come from the Bible.
A.that
B.which
C.and
D.but
差压式流量表是根据节流造成压差的原理制成的。