Dashes

0The strategy appears to be paying off. Businesses are increasingly using the internet to source and research products, as well as sell their goods overseas. 02br
00Wi-fi and internet cafes are full of students learning English, checking out overseas courses or chatting with new friends they've made online. 02br
00But unfortunately for the government, this means that political opponents can also chat online, write blogs and set up forums - and if their movements are restricted by the government, as they often are, this is the perfect way for them to communicate. 02br
00Even if the authorities manage to block their websites and forums inside Vietnam, the content they produce will still reach the outside world. 02br
00The government has been trying various ways to restrict dissidents' use of the internet, particularly since an online anti-government petition was published earlier this year, which many people signed. 02br
00But as is often the case, the authorities' efforts at control are not keeping pace with advances in technology.02br
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00Is the following sentence of the above grammatically correct?02br
00But unfortunately for the government, this means that political opponents can also chat online, write blogs and set up forums - and if their movements are restricted by the government, as they often are, this is the perfect way for them to communicate. 02br
02br
01b00 What is the meaning of dashes ( - ) ? Is it possible to replace them by commas?02b0-