Corrected sentences:
Mighty construction machines dig, lift, and carry to help build roads and houses. Their super strength helps keep everyone safe.
Step-by-step explanation:
- In the first sentence, we list three actions: dig, lift, and carry. We put commas between the actions to make the list clear. The comma before "and" (called the Oxford comma) is optional, but it often helps readers see each item clearly.
- The verbs (dig, lift, carry) are all in the present tense, which is correct because it describes what the machines do.
- In the second sentence, the word "Their" refers back to the machines. "Helps keep" is correct because the machines' strength causes everyone to be safer.
- Both sentences end with periods to show the thoughts are complete.
Tip: Another correct way to say it using two shorter sentences is: "Big construction machines dig, lift, and carry. They help build roads and houses and keep people safe." Both versions are grammatically correct.