张旭东购房居住5年后，决定换屋，旧屋20年贷款30万元，固定利率5%，按期本利摊还。新屋总价80万元，可贷70%，旧屋要卖最低( )万元，扣除旧屋剩余房贷后，才可以充当新屋的自备款。

A．41.25
B．43.69
C．49.01
D．52.43

Many Chinese students think science subjects are ______ foreign languages.

A．more difficult as

B．less difficult than

C．much difficult than

D．so difficult as