A．reasons why mobile phones aren’t reliableB．ways to st……

Are you dreaming of taking a trip on your own Here is some advice on how to make your once-in-a-lifetime journey and how to stay safe when you get there.
Before you begin to look at places, activities and plane tickets, you must set a budget. When you search through the websites about travelling, it can be so easy to add another week here or there, or choose an extra activity. Setting a budget can avoid creating a huge bill, which starts very small.
With so many countries on this planet it is difficult to decide where to go. By narrowing down your search to voluntary work or a relaxing holiday, you can save a lot of time looking through websites.
After deciding where to go, you need to research the country. Find out when each season is. It would be disappointing if you were taking part in an outdoor-based activity and it rained most days. Look into medical information, as you may need certain medicine for certain countries. Above all, make sure you can afford to go to this country and take part in the activities you have dreamt about. Don’t raise your hopes too high before you know for certain it is within your budget.
By carrying a credit (信用) card with you at all times it is possible to stop yourself getting lost. Mobile phones are very important as well. However, do not depend completely on them, since electronic machines can break without warning. Therefore, always carry a list of emergency (紧急情况) phone numbers, names and addresses. Finally, learn a little of the language. Do not expect that the people there speak your own language. After all, you are in their country.
The last paragraph mainly tells us ______.

A．reasons why mobile phones aren’t reliable
B．ways to stay safe when travelling alone
C．the importance of carrying a credit card
D．the advantages of learning a foreign language