DNA上的外显子是（） A.不被转录的序列 B.被转录但不被翻译的序列 C.被转录也

摘录信息（共5小题；每小题2分，满分10分）
阅读下面短文，根据所读内容在文后第53至第57小题的空格里填上适当的单词或短语，并将答案转写到答题卡上。
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Some beach creatures are wonderful -- like dolphins, but others are dangerous. Here are some examples of harmful beach creatures.
Puffer Fish
Puffer Fish, found in all Japanese seas, have very interesting features. They are very easy to catch but must not be eaten because their flesh and organs contain a poison. Anyone who does eat the flesh can become sick very quickly. They may even stop breathing.
The Blue Bottle
The Blue Bottle is found in most Caribbean waters. Blue Bottles float lightly on the surface of the water but their tentacles (触须) can be as long as 10 metres. Blue Bottles are much less dangerous than some other jellyfish but they can give a swimmer a bad sting (刺) if the swimmer accidentally touches them.
Stingrays
There are many different kinds of stingrays in Mauritius waters. They usually swim and feed on the bottom of the sea. Accidents can happen if people stand on them or try to pick them up. Stingrays have a sting on their tail. These stings have poison on them. If someone is stung the wound can easily become infected.
Title :   53   

Wildlife	Where creatures live	56	What effects on men
Puffer Fish	55	● easy to catch ● unfit to eat	● become sick ● stop breathing
54	most Caribbean waters	●their tentacles being as long as 10 metres ● less dangerous	give a sting
Stingrays	Mauritius waters	having a poisonous sting on their tail	easily    57   by the sting