Many adults enjoy a cup of coffee to have extra energy on a sleepy morning, and astronauts are  no exception. But having a drink in space isn't as easy as it is on the earth. You have to come up  with a whole new way to drink, and that' s what scientists are trying to do.       "The coffee would be very hard to control in a normal cup," said physics professor Mark Weislogel. "You' d have to shake the cup toward your face and hope that some of the hot liquid floats toward your mouth. When it comes to guessing what liquids will do in new systems, we are often in the dark. "      Weislogel believes that creating a big zero - gravity cup would help improve the lives of  astronauts in space,  so he and other researchers per formed a series of experiments with liquids on the International Space Station (ISS) to see how they move upwards on surfaces in zero gravity.      In one of the tests, they placed two surfaces very close together to create a very narrow tunnel. They  wanted to see if liquid would easily flow up the tunnel.  In another test ,  the researchers tried to figure out the best angle to place the narrow tunnel at so that the liquids would travel along the corners.       The end result is a cup that doesn't look like a normal coffee cup at all. One side of the cup has a very sharp angle and, in zero gravity, the liquid naturally "flows" up that angled side of the cup, right up to the drinker' s lips.       The zero-gravity coffee cup is currently being tested on the ISS by astronaut Don Pettit, who worked with the researchers and helped them invent it.  " As you sip    ,  more liquid keeps coming ,  and you can enjoy your coffee in a weightless environment - clear down to the last drop, " said Pettit, who thinks that future humans on Mars will be using this kind of cup to drink during celebrations ! According to Pettit, we can learn the coffee cup is   _  .
practical weightless shapeless awkward
Question: Many adults enjoy a cup of coffee to have extra energy on a sleepy morning, and astronauts are  no exception. But having a drink in space isn't as easy as it is on the earth. You have to come up  with a whole new way to drink, and that' s what scientists are trying to do.       "The coffee would be very hard to control in a normal cup," said physics professor Mark Weislogel. "You' d have to shake the cup toward your face and hope that some of the hot liquid floats toward your mouth. When it comes to guessing what liquids will do in new systems, we are often in the dark. "      Weislogel believes that creating a big zero - gravity cup would help improve the lives of  astronauts in space,  so he and other researchers per formed a series of experiments with liquids on the International Space Station (ISS) to see how they move upwards on surfaces in zero gravity.      In one of the tests, they placed two surfaces very close together to create a very narrow tunnel. They  wanted to see if liquid would easily flow up the tunnel.  In another test ,  the researchers tried to figure out the best angle to place the narrow tunnel at so that the liquids would travel along the corners.       The end result is a cup that doesn't look like a normal coffee cup at all. One side of the cup has a very sharp angle and, in zero gravity, the liquid naturally "flows" up that angled side of the cup, right up to the drinker' s lips.       The zero-gravity coffee cup is currently being tested on the ISS by astronaut Don Pettit, who worked with the researchers and helped them invent it.  " As you sip    ,  more liquid keeps coming ,  and you can enjoy your coffee in a weightless environment - clear down to the last drop, " said Pettit, who thinks that future humans on Mars will be using this kind of cup to drink during celebrations ! According to Pettit, we can learn the coffee cup is   _  .
A. practical
B. weightless
C. shapeless
D. awkward
Answer: