Answer:
a) Her students <u><em>are observing</em></u> a moment of silence.
b) Francine <u><em>is studying</em></u> her Spanish lesson now.
c) Water <u><em>freezes
</em></u> at 0°C
d) It <u><em>boils</em></u> at 100°C
e) The water for the tea <u><em>is boiling</em></u> now.
Explanation:
The simple present tense form of the verb is used to describe or talk about an action that is currently happening or that happens often. It uses the simple form of the verb.
Present continuous tense is used to talk about an event that is ongoing or is bound to happen, an act that is still going on. It uses the "verb+ing" form of the verb.
The correct verbs in parenthesis are given as follows-
a) Her students <u><em>are observing
</em></u> a moment of silence. (Present continuous tense).
b) Francine
<u><em> is studying</em></u> her Spanish lesson now. (Present continuous tense).
c) Water <u><em>freezes </em></u>at 0°C
. (Simple present tense).
d) It <u><em>boils </em></u>at 100°C
. (Simple present tense).
e) The water for the tea <em><u>is boiling</u></em> now. (Present continuous tense).