她对海鲜过敏，所以从来不吃虾和螃蟹。

tā duì hǎixiān guòmǐn, suǒyǐ cónglái bù chī xiā hé pángxiè.

She is allergic to seafood, so she never eats shrimp or crab.

每到春天他就过敏，眼睛又红又痒。

měi dào chūntiān tā jiù guòmǐn, yǎnjing yòu hóng yòu yǎng.

Every spring he gets allergies, and his eyes become red and itchy.

你最好先试一下，看看皮肤会不会过敏。

nǐ zuìhǎo xiān shì yīxià, kànkan pífū huì bu huì guòmǐn.

You'd better try it first to see if your skin will have an allergic reaction.