A:X+2
B:X2-
C:X2+
D:X-2
地球上所有的生物共有一个家,这就是____ 。它包括____ 、____ 和____ 。
No matter how hard it is, the strongwilled mother will never________the hope to find her lost son.
如图所示是人体关节、肌肉的结构,请据图回答下列问题
We haven't seen her for many days and there is ______ for her safety.