Vitamin D helps our bodies make a special chemical,and this special chemical,__________,affects our brains,making us feel happy.
—Can I use your phone?—______.
I was really busy these days, otherwise I _______ to your birthday party last night.
The company is quite honest and guarantees the new product ______ be under warranty for three years.
—Haven’t seen Lucy recently. What’s happened?—Oh, it’s more than two months ______ she worked here.
I saw a woman running toward me in the dark. Before I could recognize who she was, she had run back in the direction ______ she had come.