All the students are advised to keep a ____ (balance) diet for their health.
下面关于常见仪器的使用方法正确的是( )
下列关于生物生殖和发育的说法中正确的是( )
下列原子或离子的电子排布的表示方法中,正确的是____,违反了能量最低原理的是____,违反洪特规则的是____.
①Ca2+:1s22s22p63s23p6
②F﹣:1s22s23p6
③
④Cr:1s22s22p63s23p63d44s2
⑤Fe:1s22s22p63s23p63d64s2
⑥Mg2+:1s22s22p6
⑦