The plural form for the noun must is musts. The word must is also a verb, an auxiliary verb, and an adjective.
The contraction of "must not" is spelled mustn't (a prohibition, only used in present tenses).As with other contractions of "not", the apostrophe replaces the missing O.
The present participle is taking.
* I am * you/we/they are * he/she/it is
to rot
"Am" is the present participle.Present participle is the ing form of the verb and for am that is being
The changes to the rock must occur in solid form.
water vapour
Oxygen
For the oxidation of iron to occur, that is for ferric oxide to form, there must be oxygen present. There must also be water present.
The Sun
Cool air and dust Particles
High Relative Humidity
Pressure and heat.
Water vapor and heat must be present for clouds to form. The water is evaporated from the ground and collected into a cloud.
To form the present perfect tense, a past participle must be combined with the helping verbs, have, or has (present tense). In this case the verb is 'to be' and its past participle is 'been.' The answer is, "He has been ill."
If all elephants have trunks, then they must be present.
water vapour/ cold /and a condensation medium