【推荐1】语法填空
（1）________ starts as fun usage of apps turns into tremendous pressure in real social media interaction at secondary school.
（2）—It’s my treat today. Is there anything particular you would like to have?
—________ you choose is fine with me.

【推荐2】It is well­ known to the world ________ Mark Twain was a great American writer. (用适当的词填空)

【推荐3】_____ it turns out to be a good idea is still unclear. (用适当的词填空)