.的质量 是 the quality of 还是for?

.的质量 是 the quality of 还是for?
.的质量 是 the quality of 还是for?

.的质量 是 the quality of 还是for?
当然是 the quality of,看下面的例句：
He examined the quality of the furniture carefully.
他仔细检查家具的品质.

the quality of

当然是 the quality of sth.