元素的化学性质主要决定于原子的（ ）
A．质子数
B．中子数
C．电子数
D．最外层电子数
A、元素的化学性质主要决定于原子的最外层电子数，和质子无关故此项错误．
B、元素的化学性质主要决定于原子的最外层电子数，与核内中子数无关，此项错误．
C、元素的化学性质主要决定于原子的最外层电子数，和核外电子数无关，此项错误．
D、元素的化学性质主要决定于原子的最外层电子数，此说法正确．
故选D
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| Roberta appeared on the stage. She took a deep breath and began to 1 . Now she was Portia, a strong-willed 2 in Shakespeare's The Merchant of Venice. The theater was filled with people. She was speaking with a power she had never before experienced, the words flowing 3 form her 4 , Roberta had never acted in her life before the audition (选拔试演). She 5 being in front of other people. She was very 6 at school. She had never thought she was good enough at anything to 7 much attention. She stayed mostly to herself, making 8 friends. She had excellent grades, 9 she always thought that something was missing. Two weeks before the audition, Robertsa's mother had heard about it and 10 her to join in. "I can't think of anyone else better suited to 11 the part. Remember all the plays you used to act our for us?” Her mother wouldn't let the 12 drop. “You're just a little scared (害怕). Everyone gets scared. You know you 13 do it. The trick is to look past the 14 to find the love of what you're doing.” So Roberta had made an appointment (预约) with the head of the Drama Club. She had read the play and found herself excited by the 15 of speaking such rich words. In secret she practiced Portia's part, 16 the lines by repeating them over and over. It wasn't hard; she 17 every minute of it. Every time she spoke the words, she had a new 18 of the lines, as if Shakespeare had written Portia on many levels. On the day of the audition, she 19 two of Portia's famous speeches for the auditors. When she had finished, the head of the Drama Club announced the 20 was hers. | ||||
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