青少年应挑食、偏食,常导致某些疾病的发生,下列疾病与病因对应错误的是( )
A:夜盲症﹣缺乏维生素B1
B:佝偻病﹣缺乏含钙的无机盐
C:坏血病﹣缺乏维生素C
D:贫血﹣缺乏含铁的无机盐
Some people worry that robots will take the place of humans ____ the ____.
如图是元素周期表中氯元素的有关信息,下列说法错误的是( )
____
3D printers are still _____ expensive for most of us ______ afford. ( )