Let's look at your sentence and check its grammar step by step.
Your sentence is: "Like many water birds, Mandarin ducks have webbed feet that work like natural flippers. These special feet help them swim fast and smoothly and let them dive underwater where they can catch fish."
Here's what we notice:
- "Like many water birds," is a good introductory phrase that correctly compares Mandarin ducks to other birds.
- "Mandarin ducks have webbed feet that work like natural flippers." This part is clear and grammatically correct.
- "These special feet help them swim fast and smoothly and let them dive underwater where they can catch fish." This sentence is mostly correct, but it could be clearer with a comma or a connecting word to separate the two ideas.
A corrected version could be:
"These special feet help them swim fast and smoothly, and they let them dive underwater where they can catch fish."
This addition makes it clearer that the feet do two things: help the ducks swim well, and let them dive to catch fish.
Final corrected sentence:
"Like many water birds, Mandarin ducks have webbed feet that work like natural flippers. These special feet help them swim fast and smoothly, and they let them dive underwater where they can catch fish."