根据下列各句句意和空白之后的汉语提示词，在答题卡指定区域的横线上写出对应单词的正确、完整形式，每空只写一词。
John is such a _______(好奇的) boy, always asking questions.
George wants to major in _______(文学) in his further study.
Teenagers often have difficulty _______(表达) themselves.
The plane crashed, killing all 157 passengers_______(在飞机上).
He put his hand on her________(肩膀), but she threw it off angrily.
This has forced airlines to ________(打折) fares heavily in order to spur demand.
It’s unfair to soldiers who have ________(为…服务) their country well for many years.
He has a good command of the basic rules of _______(语法).
_________ (粗略地) speaking, we receive about fifty letters a week on the subject.
Jack started playing the guitar when he was _______(十四) years old.