Page 231 - Basic English Usage

233 300 — 301

300 since (conjunction of time): tenses

Since can be a conjunction of time. The tense in the since-clause can be
present perfect or past, depending on the meaning. Compare:
I've known her since we were at schoo! together.
I’ve known her since I’ve lived in this street.
Note that the tense in the main clause is normally present perfect (see
243.4-6; 244.3).
I’ve known her since ... (NOT #knewHersince ... )

301 singular and plural: spelling of plural nouns

If the singular ends in consonant + -y (for example -by, -dy, -ry, -ty),
change yto /and add -es.
Singular Plural

...consonant + y | ... consonant + ies

baby babies
lady ladies
ferry ferries
party parties

2 If the singular ends in ch, sh, s, x or z, add -es.
Singular Plural

-ch/-sh/-S/-x/-Z | -ch 1es/-shes/-Ses/-xes/-Zes
church churches
crash crashes
bus buses
box boxes
buzz buzzes

3 With other nouns, add -s to the singular.
Singular Plural Singular Plural
chair chairs boy boys
table tables girl girls

4 Some nouns ending in -o have plurals in -es. The most common:
Singular Plural
echo echoes
hero heroes
negro negroes
potato potatoes
tomato tomatoes