问题 问答题

一个电热水器的铭牌如表.求:

型号DSZF50-J
额定电压(V)220
额定容量(L)50
额定功率(W)1500
额定频率(Hz)50
最高水温(℃)75
(1)电热水器正常工作时的电阻;

(2)正常工作时通过它的电流;

(3)正常工作0.5h消耗的电能是多少千瓦时?

答案

U=220V,P=1500W,t=0.5h,

(1)R=

U2
P
=
(220V)2
1500W
≈32.3Ω.

答:电热水器正常工作时的电阻为32.3Ω.

(2)I=

P
U
=
1500W
220V
≈6.8A.

答:正常工作时通过它的电流6.8A.

(3)P=1500W=1.5KW,

W=Pt=1.5kW×0.5h=0.75kW•h.

答:消耗的电能是0.75kWh.

单项选择题

LIPITOR

ABOUT LIPITOR

Lipitor is a prescription medicine. Along with diet and exercise, it lowers "bad" cholesterol (胆固醇) in your blood. It can also raise "good" cholesterol.

Lipitor can lower the risk of heart attack in patients with several common risk factors, including family history of early heart disease, high blood pressure, age and smoking.

WHO IS LIPITOR FOR

Who can take LIPITOR:

· People who cannot lower their cholesterol enough with diet and exercise.

· Adults and children over 10.

Who should NOT take LIPITOR:

· Women who are pregnant, may be pregnant, or may become pregnant. Lipitor may harm your unborn baby.

· women who are breast-feeding. Lipitor can pass into your breast milk and may harm your baby.

· People with liver(肝脏) problems.

POSSIBLE SIDE EFFECTS OF LIPITOR

Serious side effects in a small number of people:

· Muscle(肌肉)problems that can lead to kidney(肾脏) problems, including kidney failure.

· Liver problems. Your doctor may do blood tests to check your liver before you start Lipitor and while you are taking it.

Call your doctor right away if you have:

· Unexplained muscle pain or weakness, especially if you have a fever or feel very tired.

· Swelling of the face, lips, tongue, and/or throat that may cause difficulty in breathing or swallowing.

· Stomach pain. Some common side effects of LIPITOR are:

· Muscle pain

· Upset stomach

· Changes in some blood tests

HOW TO TAKE LIPITOR

DO :

· Take Lipitor as prescribed by your doctor.

· Try to eat heart-healthy food while you take Lipitor.

· Take Lipitor at any time of day, with or without food.

· If you miss a dose (一剂), take it as soon as you remember. But if it has been more than 12 hours since your missed dose, wait. Take the next dose at your regular time.

Don’ t:

· Do not change or stop your dose before talking to your doctor.

· Do not taking new medicines before talking to your doctor.

Which of the following is a common side effect of taking Lipitor?()

A.Face swelling.

B.Upset stomach.

C.Kidney failure.

D.Muscle weakness.

判断题