题目

Find ways to respond to a major disaster When natural disasters like hurricanes and earthquakes happen, there’s always a great need for coordinated(协调的) disaster relief (安慰）and recovery（痊愈）.  16  . Volunteer To take a hands-on approach to disaster recovery, volunteer your time and talents. You can travel to the affected regions to provide support.  17  .It is recommended （建议）that you volunteer through one of the professional organizations for your safety and your skills can be put to best use. Donate（捐赠）money Disaster victims often have lost th3．在边长为2的正方形ABCD中，E，F分别为BC和DC的中点，则$\overrightarrow{DE}$•$\overrightarrow{BF}$=（　　）A．-$\frac{5}{2}$B．$\frac{3}{2}$C．-4D．-2