如图，在四棱锥P﹣ABCD中，底面ABCD为菱形，∠BAD=60°，Q为AD的

中点．

若PA=PD，求证：平面PQB⊥平面PAD

下列标志中属于质量安全标志的是（　　）

1949年以来中国在消除贫困、提高人民生活水平方面取得了巨大成就，显示了社会主义制度的优越性。我国基本建立了社会主义制度的标志是（　　）

This is a photograph ____our village.

Our village is in a valley.

It is between ____hills.

The village is on a ____.

Here is another photograph of the ____.

My wife and I ____ walking along the banks of the river.

We are on the left.

There is a boy in the water.

He is ____ across the river.

Here is ____ photograph.

This is the school building.

It is beside ____park.

The park is on the right.

Some ____ are coming out of the building.

Some of them are ____ into the park.