直角三角形的两边长分别为16和12,则此三角形的外接圆半径是____ ．
查字典
“拎”按部首查字法应查____部，再查____画，组词____
地球内部圈层的划分依据是（ ）
After over 20 years' hard work, the people ____their hometown ____ a modern city.
Grace doesn't like math because she thinks it is ________.
