Here's the answer:
“私たちはタクシーに乗らなくてはいけません”
(watashi tachi wa takushī ni nora naku te wa ike masen)
Watch a real native speaker say it:
Here's how it sounds in a textbook:
Fun fact: the hundreds of thousands of people learning Japanese with Memrise get this phrase correct 98.13% of the time!
