过正三棱柱底面一边的截面是（　　）

A．三角形

B．三角形或梯形

C．不是梯形的四边形

D．梯形

Adult butterflies use their senses of sight, touch, hearing, smell, and taste to survive in the world, find food and mates, lay eggs in an appropriate place, migrate, and avoid hungry predators.

Sight

Butterflies have large, compound (multifaceted) eyes, which allow them to see in all directions without turning their heads. Like most insects, butterflies are very nearsighted, so they are more attracted to a large stand of flowers rather than individual plants. Butterflies do not "see" colors such as red, green, and yellow, but sense polarized（偏振的） light, which indicates the direction the sun is shining, as well as ultraviolet light, which is present on many flowers and guides butterflies to nectar （花蜜）sources.

Smell

Butterflies have a very well-developed sense of smell, but it's not in their nose (since they don't have one). Sense receptors located in their antennae, feet, and many other parts of the body help butterflies find food (usually flower nectar), and mates (the female smells the male's pheromones).

Taste

Butterfly's feet have sense organs that can taste the sugar in nectar, letting the butterfly know if something is good to eat or not. Some females also taste host plants in order to find appropriate places to lay their eggs. Adult butterflies and moths feed using a proboscis, a long, coiled tube. Butterflies force blood into the tube to straighten it out, allowing them to feed. Butterflies get all their food from this tube.

Hearing

Butterflies don't have ears. Instead they "hear" sounds through their wings by sensing changes in sound vibrations.

Butterflies may possess senses we don't even know about yet because their anatomy is very different than ours, and therefore difficult to understand when perceived through our own human senses.

小题1:From the passage we can know that butterflies can see_____

A．thing behind them

B．thing in the distance

C．most bright colors

D．flower nectar from a distance小题2: Butterflies can easily find food resources by using their______.

A．sense organs of sight and smell

B．sense organs of sight and taste

C．sense organs of smell and hearing

D．sense organs of smell and taste小题3: How do butterflies feed themselves?

A．by using their feet

B．by using a tube.

C．by using sense receptors

D．by using their wings.小题4:What is the passage mainly about?

A．The food sources of butterflies.

B．The habits of butterflies.

C．The unusual body of butterflies.

D．the sense of butterflies.