---How long did it _____ you to work out the difficult maths problems?

---I ______ about half an hour on it .

A．take ; took

B．spend ; took

C．spend ; cost

D．take ; spent

毛 * * 思想的成熟是在

A．中 * * 党创立和国民革命时期

B．土地革命战争前中期

C．土地革命后期和抗日战争时期

D．解放战争时期和新中国成立后