灰分的酸度和碱度
参考答案:
是指100克食品的灰分溶于水中,用0.1M酸或碱的规定溶液中和时,所消耗酸液或碱液的毫升数,即为食品灰分的酸、碱度。以+表示碱度,以-表示酸度。
We often provide our children with toys, footballs or basketballs, ______ that all children like these things. [ ]
A. thinking
B. think
C. to think
D. thought
心动周期中,实现心室血液充盈的主要机制是()
A.血液的重力
B.心房收缩的挤压
C.胸膜腔内负压
D.心室舒张的抽吸
E.骨骼肌收缩的挤压