在CH3COOH 与CH3CH218OH 酯化反应后的生成物中,18O存在于( )
A:乙酸
B:乙醇
C:乙酸乙酯
D:水
________my father ________ my mother is able to drive a car. So they are going to buy one.
填上合适的单位。
①火柴棒的长度是5____。
②小名的身高130____ 。
③操场的跑道长度是400____。
④一棵杨树高12____ 。
印度是世界第二软件大国,软件出口量仅次于( )
Parents today also worry about their children's diets. Some doctors give the following advice: