Если он купит туфли без примерки, е

Если он купит туфли без примерки, ему придется обменять их, если они не подойду ему по размеру.

Результаты (английский) 1:

If he buys a pair of shoes without trying, he'll have to swap them if they don't come to him.

Результаты (английский) 2:

If he would buy shoes without trying them on, he will have to exchange them, if they do not go up to him in size.

Результаты (английский) 3:

if he wants to buy shoes without trying, he will exchange them if they didn"t get him fit.