题目

We are all called upon to make a speech at some point in life , but most of us don’t do a very good job . This article gives some suggestions on how to give an effective speech . So , you have to give a speech—and you’re terrified . You get nervous , you forget what you want to say , you stumble over words , you talk too long , and you bore your audience . Later you think , “Thank goodness , it’s over . I’m just no good at public speaking . I hope I never have to do that again .” Cheer up ! It doesn’t have to be that bad . Here are some simple steps to take the pain out of spee8．原核细胞不同于真核细胞的主要特点是没有（　　）A．DNAB．核膜和核仁C．细胞膜D．细胞壁