物质的性质决定其用途．下列因果关系不成立的是（　　）

A．洗洁精具有乳化功能，用于去除油污

B．磷燃烧能产生白烟，用于制作烟幕弹

C．钨的熔点高且能导电，用于制作白炽灯丝

D．铁的活泼性比铝弱，铁制品比铝制品在空气中更耐腐蚀

(A) 条件(1)充分，但条件(2)不充分．
(B) 条件(2)充分，但条件(1)不充分．
(C) 条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分．
(D) 条件(1)充分，条件(2)也充分．
(E) 条件(1)和条件(2)单独都不充分，条件(1)和条件(2)联合起来也不充分．

A survey of 600 computer owners revealed that they owned a modem and/ or a scanner. How many of the people surveyed owned only a modem
(1) The number of people surveyed who owned only a modem was three times the number of people who owned only a scanner.
(2) Four hundred people who were surveyed owned both a modem and a scanner, which was eight times the number of people surveyed who owned only a scanner.