pear是不是可数名词

例句：

She bit into a ripe juicy pear.

她咬了一口熟透了的.多汁的梨。

Pear trees are grafted on quince rootstocks.

梨树被嫁接到榅桲的根茎上。

In gardens, cankers are most prominent on apples and pear trees.

花园树木中患溃疡病最多的是苹果树和梨树。