in on at
subject verb agreement
100

I eat ____ the afternoon.

in

100

He live in Guatemala. 

lives

200

I will go to the mall _____ Saturday.

on

200

I walk in the afternoons. 

correct
300

It is cold ____ the wintertime. 

in

300

You sings very good. 

sing

400

I wake up ____ 6:00.

at

400

We watches a movie. 

watch

500

It rained ____ night. 

at

500

She runs fast in the race. 

correct