b buy - bought (irregular)
1 become - became -( irregular)
2 stop - stopped - (regular)
3 build - buiIt - (irregular)
4 cancel - cancelled -(regular)
5 learn - learnt -(irregular)
6 understand - understood -(irregular)
7 fly - flew - (irregular)
8 dream - dreamt/dreamed- (both)
9 find - found - (irregular)
10 laugh - laughed - (regular)
11 travel - travelled- (regular)