溶酶体具有细胞内消化功能，其内部水解酶的最适pH在5.0左右。下列叙述错误的是（　　）

9□475≈10万，在□里最小填____；12□0001000≈12亿，在□里可以填____．

我国人口分布大致有一条人口地理分界线，是（    ）

推理填空：
如图，已知∠1=∠2，∠B=∠C，可推得AB∥CD．理由如下：
因为∠1=∠2（已知），且∠1=∠4（①理由：____ ）
所以∠2=∠4 （等量代换）
所以CE∥BF （②理由：____ ）
所以∠C =∠3（③理由：____  ）
又因为∠B=∠C（已知），
所以∠3=∠B（等量代换）
所以AB∥CD （④理由：____ ）

阅读短文，从方框中选择适当的词并用其正确的形式填空，使短文通顺、意思完整。请每空限填一词，每词限用一次。方框中有两项多余的。

Are you still doing the V for victory sign? It's out. The latest popular hand gesture（手势）is putting both of your hands and put them together to make a heart—shape. It is  ____ “hand heart”.

 Many young pop    ____  in the US have done the move in recent photos. “The‘hand heart’gesture means something    ____   'I love you' and 'thank you’, ”said Taylor Swift,the country singer.  “You can send a sweet，simple message without ____  a word.”
 Swift often does it at her concerts. And she is believed to be the first to   ____  it popular.
 Last month，Justin Bieber and____ uperstar friends did the “ hand heart” and put the photos online.They did it to help out three kids whose parents were killed in a car accident.

“It used to take much  ____  for nonverbal（非语言的）culture to move. But now ,It moves faster____ we have smart phones and the Internet.
In the Republic of Korea, the “hand heart “ has been  ____  for a long time, but in a different  ____  . People there put their hands above their heads and making a bigger heart shape with their arms. It means: “I love you.”