Imagine this: you wake up each morning to find your sister lying beside you. To get dressed and tie your【B1】______, you use one

Imagine this: you wake up each morning to find your sister lying beside you. To get dressed and tie your (26) shoes, you use one hand and she uses another, you do everything else together too, even sitting on the same chair (27) at lunch and riding on the same bicycle. That’s what life is like for six-year-old Betty and Abey. Like most (28) twins, the two girls look very much alike. But unlike most twins, Betty and Abey (29) share parts of the same body. Twins like Betty and Abey are (30) rare, only about 40 sets are born in the United States each year.
Few (31) survive as long as Betty and Abey. That is because twins often share vital organs like a heart or brain. These shared organs are often badly (32) shaped, and may not be strong enough to support both twins.
But Betty and Abey each had her own head, heart and stomach which function normally. The girls share 3 or 4 lungs which provide (33) plenty of oxygen for both twins. Most their completely shared organs lie below the waist. Betty and Abey live relatively normal lives, they attend a regular school and each does her own school work. They (34) prefer to do some projects together, though. For example, to cut out paper dolls, one twin holds the paper while the other uses the scissors. But sometimes the girls don’t want to do the same thing. (35) For example, sometimes they want to play with different toys. What do they do then? “We cast a coin,” says Abey.