下列生物中，没有细胞结构的是（ ） A．变形虫 B．真菌 C．病毒 D．细菌和放

Here are reports of three attacks (攻击). Three swimmers were attacked by sharks (鲨鱼) because they didn't obey (遵守) the safety rules for swimmers.

Rules for swimmers: 1. Don't swim at night. 2. You are more likely to be attacked in warm water. 3. Sharks are attacking by blood (血). Don't swim with an open cut（划口）. 4. It's best to wear a swimming suit to match(与……相配) your skin colour. Sharks can see colours. 5. If you see a shark, don't be nervous. Try to swim quietly, with even (平稳的) strokes (划水动作).

Report 1_: Colin was swimming with two friends very late at night. He was attacked by a shark and died.
Report 2_: Ann was a very good swimmer. She bought a new bright red swimming suit. She was swimming with some friends when a shark attacked her.
Report 3_: Jack was on holiday in Australia. He cut his foot on the beach. He went swimming the same day and got at­tacked.
阅读上面的材料，完成下列句子。(每空一词)
小题1:Colin was attacked by a shark and died because he was swimming with two friends very late at ________.
小题2:It’s not a good idea to wear a ________ red swimming suit like Ann, because sharks can see colours.
小题3:You mustn’t go swimming with an open _________.
小题4:If you see a shark, try to swim ________, with even strokes.
小题5:You can be _________ only if（只要） you obey the safety rules for swimmers.