Answer:
1. Currently, the police <u>know</u> of no motive for the crime. Present
2. Have you <u>spoken</u> to anyone about your vacation plans? Past Participle
3. Who <u>saw</u> your solar calculator last? Past tense
4. The senior choir has <u>sung</u> a medley of show tunes. Past Participle
5. Our lawn mower <u>ran</u> out of gas before I finished the lawn. Past tense
6. Who could have <u>stolen</u> such a heavy statue? Past Participle
7. I have <u>written</u> several poems for the school newspaper. Past Participle
8. The team <u>swam</u> warm-up laps before the meet. Past tense
9. Who has <u>taken</u> the schedule off the bulletin board? Past Participle
10. The skittish pony <u>throws</u> everyone who tries to ride it. Present tense
Explanation:
The past tense is used to signify action that happened in the past. Some examples of past tenses as seen in the examples above are; saw, ran, and swam.
The present tense is used to signify action that is still occurring. Some examples as used in the above sentences are, throws, and know.
The past participles are coined from verbs and are used to denote actions that occurred in the past. Examples as used above are, sung, written, taken, and stolen.