例句與造句

1. at present, most of ta-nb ores are processed by use of gravity concentration, with which the recovery of fine-grained ta-nb mineral is very low
   目前鉭鈮礦的選礦多以重選為主，但重選法選別細粒鉭鈮礦的回收率非常低。
2. It's difficult to find use of gravity in a sentence. 用use of gravity造句挺難的