English & Language Usage

"Their" is the possessive form (their books). "There" indicates place; "they're" = they are.

"Its" is possessive (the cell lost its membrane). "It's" is the contraction for "it is" or "it has."

"Affect" is usually a verb (to influence); "effect" is usually a noun (a result).

Drop the silent e before a vowel suffix: hope + ing = hoping; care + ed = cared.

If a word ends in a consonant + y, change y to i before a suffix (except -ing): happy + ness = happiness; carry + ed = carried.