ページ3:

○If it were not for your help, I could not succeed.
もし君の助けがないなら、 私は成功できないだろうに。
○If it were not for his idleness, he would be a nice fellow.
怠惰でなければ、 彼はいいやつなのだが。
○If it were not for exams, we would be happy.
試験がなければ、 私たちは幸せなんだが。

ページ4:

並べ替え問題!
コンピューターがなければ、 私たちの暮らしはもっと不便でしょう。(1語不要)
(it / not / but / were / for / if) computers, our lives would be much more inconvenient.
↓
if it were not for (but不要)

ページ5:

唱えましょう
if it were not for もし... がなければ
if it were not for もし... がなければ
if it were not for もし... がなければ
if it were not for もし... がなければ
if it were not for もし…がなければ