用适当的介词填空
(1)He was born____ a cold morning.
(2)The girl began to learn to play the piano____ an early age.
(3)The beautiful music was____ Gu Jianfen.
(4)We often watch concerts____ TV.
(5)The boy can play all types____ instruments(乐器).
如图,PA,PB,分别切⊙O于点A,B,∠P=70°,∠C等于____ 。
在一定条件下,分别以高锰酸钾、氯酸钾、过氧化氢(2H2O2 =2H2O+O2↑)为原料制取氧气,当制得相同质量的氧气时,三个反应中转移的电子数之比为 ( )
Jim records his physical training every time so that he can________it and think about how he should improve it the next day.
— Let's ________ football this afternoon.
— Sorry, I like going __________.