不同频率的电磁波的传播速度都相同，当电磁波的频率改变时它的 ______也会改变

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56．If you want to find more information about hotels with breakfast, which of the following websites can you go to ?
A．www.HIExpress. Com/HongKong               B．www.agoda.com/Hong-Kong-hotels
C．Four Seasons.com/hongkong                       D．Booking.com/hotels-hong-kong
57．At a discounted hotel, how much can you save for a room for HK$200per night?
A．HK$150                         B．HK$100                         C．HK$50                  D．HK$75
58．From the ads above we know that              
A．Hong Kong Hotels guarantee low rates and free computers
B．guests can give reviews on the hotel they have lived in
C．booking a hotel online is quite a special offer
D．experience in Hong Kong is an expensive night