已知|a|=6，|b|=4，且a＜b，则a+b的值为（　　）

非洲矿产资源种类多，储量大．____ 、____ 、____ 、____ 等的储量都居世界前列．

左图是我国南方某大城市地铁线分布图，右图Ⅱ是该城市某地铁站一天中部分时段进出站人数统计图，读图，完成下列问题。

    Picture this scene. You wake up on a school morning, and you know you're 1. Maybe your throat is sore. Maybe your head hurts. Whatever the 2 is, your mum or your dad sends you back to bed to rest. This 3 to every kid once in a while, right?

    Wrong. And the living proof (证据) is eighteen-year-old Travis Schmidt. From his first day of kindergarten (幼儿园) to his last day of high school, Travis 4 stayed home sick. At first, Travis didn't think too much about never being absent (缺席的). But then he reached third grade with perfect attendance (出勤率). At that point, Travis decided to see how 5 he could keep it up.

    So how did Travis successfully keep 13 years of perfect attendance? In the first place, he's a very heathy kid. Although he got colds like everyone else, Travis never felt sick enough to stay home. Travis also 6 ahead (提前地). For example, he knew he'd 7 get chickenpox (水痘) sooner or later. So when a friend caught chickenpox one summer, Travis made sure to 8 him. A few days later, he was covered with poxes. But he had quite a lot of 9 to get better before school started in autumn.

    Travis is 10 his record. "I may not be the smartest or the coolest. But I'm always there," he says.

1943年2月，罗斯福在致斯大林的一封贺信中说：“是你们制止了侵略浪潮，成为盟军反侵略战争的转折点。”这一“转折点”是指