harmful metal的用法和样例：
例句
- Calcium citrate is also used as a water softener because the citrate ions can chelate unwanted metal ions.
柠檬酸钙也可以用来作为水柔软剂，因为柠檬酸离子螯合有害金属离子。 - The pro and con of using these methods were analyzed, and the application of other possible methods of harmful metals in tobacco was previewed.
作者简述了各种方法的优缺点，展望了其它有害金属检测方法在烟草中的应用。
