1. Look at this sentence from Sweet tooth (Ch1):
“Jobs were hard to find”
In this sentence, the basic structure looks like this: Subject + to be + adjective + infinitive
2. Complete the following sentences using the correct adjective + infinitive
simple to use/difficult to change/difficult to answer/easy to read/difficult to understand
a. Their accents were ______, so I asked them to repeat what they said.
b. The book was ______, so I finished it in just three days.
c. One of the exam questions was ______, so I went back to it later and tried again.
d. The tire was ______, but luckily there was a garage nearby.
e. The iPhone 5 is ______, but it is quite expensive.
For more practice with infinitives, try this site: http://www.grammar-quizzes.com/infinitive4.html