1.All of the balloons on the string (popped) except two.

Question

2.Do you (want) to buy those books?
3.Daniel's dog is (following) the trail to the river's edge.
4.For thirty years the noon whistle has (blown) exactly on time.
5.The players have (challenged) their parents to a game of soccer.

I have to tell if the verb form in () is base form, present participle, past, or past participle.

1.past
2.base form
3.present participle
4.past participle
5.past

Answer 1

2) Isn't "base form" the infinitive? This is not the infinitive but the Present Indicative Tense.
to want = base form
you want, you DO want, you ARE wantING = all forms of the Present Indicative Form.

I don't know what your text book is, but the above is what it is to me.

Sra (aka Mme)