1. Couldn't
I couldn't sleep.
The bridge couldn't sustain the force of the strong current and collapsed.
Last year, I couldn't spend as much time with my children as I wanted to.
Couldn't we cuddle, instead?
When I fell off my bicycle, I couldn't get up for a few minutes.
This guy is really wishy-washy. He couldn't make a decision to save his life.
Tom asked me to do him a favor. However, I couldn't do what he asked.
Imagine if you started hiccoughing and you couldn't stop.
That knife wasn't sharp and I couldn't cut the meat with it, so I resorted to using my pocket knife.
I usually take a shower after I play tennis, but today I couldn't.
I overslept and consequently couldn't join them.
I became very nervous when I couldn't locate my passport.
The police spent hours searching Tom's place, but they couldn't find the murder weapon.
I looked in my closet for something to wear, but couldn't find anything appropriate for the occasion.
I received a letter from her to the effect that she couldn't accept my marriage proposal.