помогите плиз! нужно вставить a, the или ничего lets arrange.... party

 1.Let's arrange  a party  at the wekend.

2 It's a lovely day , isn't it?

3 he is in the fifth form , isn't he?

4 The Serovs visited London in March.

5 Linda is going to visit Finland next month.

6 Would you like to stay with the Browns?

7 They are going to have a picnic and have a good time.

lets arrange a party at the  weekend. its a lovely day, isn't it? he is in the  fifth form, isn't he? the Serovs visited London in March. Linda is going to visit Finland next month. would you like to stay with the Browns? They are going to havea picnic. have a  good time!