Fats and fixed oils are greasy or waxy substance that ill their pure state are normally tasteless, colorless, and odorless.（） A: or B: substance C: their D: normally

The inner layer of the exoskeleton (外骨骼) of an arthropod is called the ________. It contains chitin (几丁质), and its outer region is hardened. The outermost layer of the exoskeleton is waxy and impermeable to water. A: epicuticle (上表皮) B: procuticle (原表皮) C: hypodermis (真皮) D: basement membrane (基膜)