помогите вставить правильные ответы
1. My sister …… at the concert last year.
a) sang b) sing
2. Sam ……. a letter yesterday.
a) write b) wrote
3. I …….. in the river last summer.
a) swim b) swam
4. I ……. a clown in the circus.
a) saw b) see
5. I ……. in the park yesterday.
a) am b) was c) were