1．Judy and Jane are twin girls，but they are different from each other in many ____________(方面)．
2．If a student ____________(缺少)the motivation to study，he or she will quickly become tired of studying.
3．The secret of happiness is to think about positive things and stay ____________(乐观的)．
4. Training is provided，so no ____________(早先的)experience is required for this job.
