题目内容：

sat it this that
peter will participate in chess competition for his school because he did well in this.
if a student studies hard,one will gain a good mark.
请问这两句话的错误,应该怎样改正
this that it分别可以指代什么不能指代什么?

优质解答

peter will participate in chess competition for his school because he does well in this.
If a student studies hard, he or she should gain a good mark.