1.The plane finally arrived on the airport _________(safe)
1.The plane finally arrived on the airport _________(safe)
这道题为什么不能用safely 要用safety?
2.The ice on the river is not thick enough for us to skate on.(保持原意)
The ice on the river is ________ _________ for us to skate on.
这题为什么不能用thin enough ,而要用too thin?