给下列句子选择合适的答语。
① It's 7 o'clock ____ A. It's time for English class.
② It's 9 o'clock ____ B. It's time for breakfast
③ It's 5 o'clock. ____ C. It's time to go home.
在交通道口等公共场所,我们经常会看到各种警示图标(如图所示)
结合所学知识回答:
关于经线和纬线的叙述正确的是( )