如图，△ABC中，∠C=90°，且AC＝BC＝4，点M满足$\overrightarrow{BM}=3\overrightarrow{MA}$，则$\overrightarrow{CM}·\overrightarrow{CB}$＝(    )

函数$f\left(x\right)=a\sin \left(\frac{1}{2}x+\frac{\mathrm{\pi }}{4}\right)x\in 0,+\infty )$的周期为____ ，振幅为____ 初相为____ ．

    Today（今天） is Sunday. The weather is warm and windy. I can wear my shirt（衬衣） and jeans牛仔裤). I fly a kite on the playground. Tom and Jack wear their T-shirt and shorts. They play football. But in Harbin, it's cold. It's snowy. People put on their coat and hats. They can make a snowman(雪人) and skate(滑雪). It's funny.

判断下面的说法是否正确。