Substantial atmosphere around planetary bodies acts as (i)_____ incoming objects. Smaller objects, particularly those that are lower in density and more fragile, (ii)_____ in the upper reaches of the atmosphere, whereas more intact, larger bodies may survive to impact the surface. Thus, relative to large craters, small craters are much less (iii)_____ on bodies with dense atmosphere, such as Earth, Venus, and Titan, than they are on Mercury and Moon.
答案：B,D,I