请根据句子的意思选择恰当的单词填空。 intensify intense intensity (1) I was amazed at my own________and the overwhelming motivation that compelled me to spend a hundred dollars on a total stranger. (2) China has faced several challenges over recent decades and come out on top. Now, its immediate challenges are more _________than ever. (3) Amazon has launched a challenge to the Apple’s iPad with a low-price tablet computer, in a move set to_______competition over the way people consume digital books, music and video.