请根据括号中的中文提示、英文释义或句意，写出句中所缺单词，使句子通顺。
Alex is crazy about computer. He wants to be a computer         （工程师）in the future.
Being tall gives him an           （优势）over the other basketball players.
The young detective decided to           （find out）the truth alone.
My father is not in.He has gone          （away from one’s own country）on business.
         people can’t hear，so they always use their hands to communicate.