用氧化还原滴定法测得FeSO4·7H2O中铁的含量为20.01%、20.03%、20.04%、20.05%。则这组测量值的平均值为______，

A．volume 2

B．volume 3

C．volume 5

D．volume 6

A．volume 2

B．volume 3

C．volume 5

D．volume 6

A. obtain a weather forecast before setting out from port

B. listen to weather forecasts on the radio while enroute

C. understand all broadcast weather warning information

D. All of the above

Weather information is available from ______．

A.Commercial radio broadcasts

B.The Coast Guard on scheduled marine information broadcasts

C.VHF-FM continuous marine weather broadcasts provided by the National Weather Service

D.All of the above

If you need more information, please contact us______telephone or email.

A．in

B．by

C．on

D．for

THE ULTIMATE RADIO PUTS THE WORLD AT YOUR FINGERTIPS

Now there is a truly portable radio that will never depend on batteries. The lnfoMate World Band Dynamo and Solar Radio is the most versatile radio ever built! This radio runs on four AA Nickel-Cadmium rechargeable batteries that are good for a lifetime. Once these four batteries are charged, they will last for approximately seven hours of continuous play. An indicator on the front warns when the batteries are low and need to be recharged.

No more batteries. One reason the InfoMate is known as the most versatile radio ever built is its four ways of being recharged. Forget the regular type of battery rechargers that need to be plugged into a wall overnight. Although the InfoMate can be recharged through an AC/DC wall adapter, it can also get seven hours of juice just from your car's cigarette lighter. If you want to take your InfoMate on the beach, you won't need new batteries at aU. It comes with a self- contained, first grade solar cell that lasts a lifetime. Three hours of sunlight will charge the radio for approximately four to six hours of playing time. If you can' t spend every day on the beach keeping it on your windowsill or another sunny spot works just as well.

The fourth way to add power to the InfoMate when it starts to fade is an ingenious hand- cranked generator hidden into the side of the radio. All you have to do is pull down the specially designed dynamo handle for "free energy" and an emergency power source. Five minutes of cranking should provide about an hour of playing time. This feature is a great alternative for power outages, outdoor use and night time situations.

Most versatile radio ever. The power options alone make InfoMate no ordinary radio. But it also has something that you cannot get on most radios found in retail electronic outlets. InfoMate gives you access to eleven different frequency bands. Not only does it have the normal AM/FM stations, it can bring you the sound portion of broadcast television shows. How many times have

we been interested in a television show or a sporting event and had to go out in the car and could not find the program on the car radio？ With the most versatile radio ever invented, you could keep up with the action while running errands or commuting.

With this versatile radio, you can also listen to worldwide foreign broadcasts on any of four short wave bands as well as taxi cab, police ambulance and commercial airline communications. Another important feature of the InfoMate radio is the band that brings you access to the National Weather Service. Keep up with current forecasts when you need them, not when radio or television stations choose to air them. If you happen to be driving through a severe storm and forgot to charge your radio, but need the latest forecasts, just plug the radio into the cigarette lighter to get the vital information you want.

Your InfoMate radio comes with four AA rechargeable batteries, and the deluxe package comes with the optional accessories of an AC/DC adapter, supersonic earplugs, and a 12 volt car cigarette charging cord. You will also get an emergency weather preparedness booklet.

Suppose you are hiking in the country. In an emergency when the batteries have run out, the best alternative to get power for the radio is______.

A．to expose the radio to the sunshine

B．to use standby batteries that are charged

C．to crank the dynamo

D．to plug it into a cigarette lighter