No. You shouldn't give your child hard foods like zwieback crackers, toasted or frozen bagels, carrots, and frozen bananas. They may appeal to a baby's intense urge to chew, but when gnawed on long enough they can come apart in choke-hazardous chunks.
The exception is if they are in mesh feeders. You can fill them with essentially any fruit or other food that's soft enough to seep through the mesh and that your baby's tried enough times to tell he's not allergic to it. He can suck and suck on the mesh, and he won't get a piece of food big enough to choke on. (There's a plastic piece, usually a teething ring that fits over the mesh; make sure it's attached tightly so your baby can't pull out chunks of food.)
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