【判断题】电流的频率不同,对人体的伤害程度也不同,一般认为50~60Hz的交流电对人体最危险。
【简答题】看图选择合适的单词填空。 pears nine gs woman watermelon 1. Can I have some ___________? 2. I can see ___________ ants. 3. The ___________ is so big. 4. Do you like ___________? Yes, I do....
【简答题】听音,根据你听到的句子内容按顺序标号。 1. Mom, can I help you? 2. My schoolbag is heavy. 3. Can I have some chicken? 4. Go to the living room. 5. Who is your best friend? 正确顺序: __________________________________
【单选题】50~60Hz的交流电对人体的伤害程度最大,当低于或高于以上频率范围时它的伤害程度就会怎样变化。
【判断题】频率在 30 ~ 60Hz 的交流电易引起人体心室颤动,常用的 50Hz 的工频交流电对人体的伤害程度最为严重。
【简答题】Read and choose.(选择合适的单词填空) pears nine gs woman watermelon 1. Can I have some _____? 2. I can see _____ ants. 3. The _____ is so big. 4. -Do you like _____? -Yes, I do. 5. -Who's...
【判断题】新型冠状病毒流行期间,要尽可能减少外出,坚持健康生活方式。养成良好的个人卫生习惯,咳嗽或打喷嚏时用纸巾掩住口鼻,不用脏手触摸口、眼、鼻,不随地吐痰。每天早中晚均应开窗通风,每次通风不少于30分钟。
【简答题】给下列的问句选择合适的答语。 ( ) 1. Do you like pears? ( ) 2. Can I have an apple? ( ) 3. Where's my cat? ( ) 4. How many balloons can you see? ( ) 5. Is he your brother? ( ) 6. Look at the ...