if I..... a word, I look it up in my dictionary
a. doesn't know b. not know c. don't know


I'm sure Sue would understand if you.... the situation
a. explain b. explained c. explains


we will go to the beach if the weather is good
a. first conditional b. second conditional c. zero conditional


if we told them the truth, they...... us
a. believed b. will believe c. would believe



if we.... Bill to the party, we would have to invite his
a. invited b. invite c. invites ​