The following words have roots with one syllable. to each, the -ing suffix has been added. which word is spelled correctly?
a. shiping
b. hiting
c. meeting
d. triming

The correctly spelled Word is meeting. All of the other words need a double consonant. So we need :shipping trimming and hitting. You know that a word needs a double consonant in the gerund form if it has a short vowel.

When a word ia a monosyllable ending with a consonant and preceded by one vowel, the last consonant has to be doubled before adding a suffix that begins with a vowel Ex, ship + p + ing = shipping
                    hit + t + ing = hitting
                  trim+ m + ing = trimming
When the last consonant is preceded by 2 vowels ,then it doesn't double .Just add 'ing'             meet + ing = meeting
                  wait +ing = waiting