A: look for
B: look after
C: look at
D: look like
①喝白开水 ②喝生水 ③睡懒觉 ④随地大便 ⑤不勤洗手 ⑥不勤潄口.
已知圆柱的底面半径为1,母线长为2,则圆柱的侧面积为( )