根据句子意思, 从方框中选择恰当的短语填空。
To my surprise; has a lasting value; in all directions; broke out were forced to ; out of breath ; gives up;
take notice of; directed; playing ; showed an interest in
在①2x+y=1；②3x﹣2y=1；③5xy=1；④x2+y=1四个式子中，不是二元一次方程的有（ ）
