A:两条线一样长
B:0°经线比0°纬线略长
C:0°经线不足0°纬线一半长
D:0°纬线比0°经线略长
It's difficult to live in a foreign country, ______ if you can't understand the language there.
舒适度指数是指人对____、____和____的综合感受。