We(ought)to spend (as much) time ( as ) we can (planning) this charity activity.
ought to do sth 应该做某事
spend some time (in) doing sth 花费时间做某事
We(ought)to spend (as much) time ( as ) we can (planning) this charity activity.
ought to do sth 应该做某事
spend some time (in) doing sth 花费时间做某事