chứng minh giá trị biêu thức ko âm ko dương

(a+c)(a-c)-b( 2a-b) -(a-b+c)(a-b-c)

The bues were very ____________this morning. We can't go to the church with you in time ( crowd)

vietnamese people are very_____________( friend)

they_________ english at the moment ( learn)

We ___________to Hung KIng Festival since last Sunday ( go)

Peter____________football yesterday.(play)

The childrent used to__________a long way to school (go)

I'd like ( visit)____________the vietnam Museum of Ethnology this weekend

Mai enjoys__________crafts, especially bracelets ( make)

_________-you ever____________-a buffalo? ( ride)

a custom is something that has become an___________- way of doing things

A: to be accpept B: to accept C: accepting D: accepted

1)during the festival, they fly many _______ kites in different shapes and sizes

A: colour B: colourless C: colourful D: colouring

2) The US is a_________country with over 80 ethnic groups

A: Multi-cultural B: Bi-lingual C: Rich D: Ethnic

3) In 2010, Ha Noi__________its 1000th anniversary

A: Celebrated B: Commemorated C: worshipped D: Remember

4) In the Central Highlands, the biggest and tallest house in the village is the___________house

A: Communicatin B: Community C: Communal D: Commune

5) The Viet people have many___________costoms and crafts

A: Tradition B: Traditional C: Culture D: Customary