某患儿夜间易惊醒,多汗,烦躁,骨变软,弯曲变形。可能与哪种维生素缺乏有关()
A.维生素A
B.维生素D
C.维生素B
D.维生素C
E.维生素E
参考答案:B
新分泌釉质基质所含矿物质仅占矿化物总量的()
A.15%~20%
B.25%~30%
C.35%~40%
D.45%~50%
E.55%~60%
The new appointment (任命) of our president _________ from the very beginning of the next semester.
A.takes effect
B.takes place
C.takes turns
D.takes part