How much of all precipitation is runoff

A．To limit discussion on heating bills.
B．To prevent heat loss.
C．To determine temperature in homes.
D．To convert homes to electric heat.

A．They look like sandwiches.
B．They can heat but not cool homes.
C．They cost about ＄300 each.
D．They are placed on rooftops.

A．They can’ t be recycled though they help people save time on housework.
B．They become trash and therefore are harmful to the environment.
C．They add cost to the product and thus make it more expensive.
D．Sometimes they are not strong enough to hold the purchase.