The children decide their school yard this Friday afternoon.
A：clean
B：to clean
C：cleaning
D：cleaned
在锐角△ABC中，若A=2B，则ab的范围是（ ）
wǎn gōng dā jiàn
____
yán lì chéng fá
shāo shú shí wù
南极洲的地理特点是（ ）
