I wondered what difficulty he had ______ the plan?[ ]

_______ was only then I reread his theory recentlyI began to appreciate their value.

The popular cartoon Mulan is a _____ of a Chinese poem for children．

__________ it is true that a student’s most important goal is to do well in his or her studies, it doesn’t need to be the only goal

Now large numbers of young people in China ________posting voice messages, articles and photos onto the WeChat (微信) to share with their friends.