Riding a bicycle is great exercise． Depending on how fast you ride，you can （1）

easily

easily

（easy） burn 700 to 1，000 calories in an hour． It helps relax the muscles in your lower body． Cycling is gentle on the joints，（2）

which

which

makes it a good choice for people who suffer from arthritis， a disease that （3）

causes

causes

（cause） pain in one or more joints of the body．
    If you decide to get started， don't try to do too much too soon．（4）

Start

Start

（start） with short rides of 10 miles or so on flat roads without a lot of traffic． When it becomes easy，you can add five miles or so． You will want to avoid big （5）

hills

hills

（hill）when cycling， but they can be an （6）

interesting

interesting

（interest） challenge if you hope to get into better shape．
    Even if it didn't do anything for your health， riding a bicycle would still be a great way （7）

to get

to get

（get）around． Bicycles don't cause （8）

pollution

pollution

（pollute）and they let you see the neighbourhood or the countryside at slow speed without a car window getting in （9）

the

the

way．
    Finally， riding for exercise or jumping on the bike （10）

for

for

fun will just become a habit，and you won't even give much thought to the fact that you are exercising．