He promised ______his old friend during his stay inTianjin.

对下列加点字的意义和用法，解释正确的一项是（ ）①蚓无爪牙之利，筋骨之强 ②未之有也③奚以之九万里而南为 ④青，取之于蓝

How do you find the health club?—I it. Everyone is saying its management is going from bad to worse.

A new iPad in the market costs about ______ of a second-hand one.

Did you enjoy the drama last night?—Yes. I’ve never seen _________ one before.