Topics: TOEFL
The horn of the rhinoceros consists of a cone of tight bundles of keratin ______________ from the epidermis.
A. grow
B. grows
C. growing
D. they grow
Preview next quiz:
The upper levels of the sun’s atmosphere are of very low ______ heats the gases there to very high temperatures.
A. dense and solar
B. density, solar activity
C. density, but solar activity
D. density and the activity of the sun is