阅读下列材料，从每题所给的四个选项(A、B、C和D)中，选出最佳选项。
A
Here's a selection of festivals for tourists to the United States in summer.
San Francisco Silent Film Festival
Films at this odd cinematic event have a variety of musical accompaniments, including piano and violin. It includes some classic silent movies. If you want to see them all, you can buy a festival pass.
May 28 to June 1; www. silentfilm.org
Union Street Festival
This popular street fair stretches out over six blocks of the city, in the fashionable shopping area of Union Street. This year, there's beer, wine tasting and more separate themesfashion, cuisine, tech, local, craft, and health and fitness.
June 7 to 10; www.unionstreetfestival.com
North Beach Festival
This is San Francisco's oldest street party, with live entertainment, delicious food and arts and crafts. Situated in the Little Italy district, known for its associations with the “Beat Generation”， festival goers are provided with plenty of good Italian food. There is also as the “blessing of the animals”， a San Francisco tradition which takes place at the National Shrine of Saint Francis of Assisi(610 Vallejo Street) at 2 pm on both days of the festival.
June 14 to 16; www.sfnorthbeach.org
Stern Grove Festival
This is the oldest free summer arts festival of its kind in the United States. It includes a wide variety of acts, from the local orchestra to well known artists such as Smokey Robinson.
Sundays from June 22 to Aug 24; www.sterngrove.org
21．Which of the following festivals contains the most themes?
A．San Francisco Silent Film Festival.
B．Union Street Festival.
C.North Beach Festival.
D．Stern Grove Festival.
22．How is North Beach Festival different from the other festivals?
A.It lasts the shortest time.
B．Festival goers can enjoy food in it.
C.It has the longest history of food.
D．Some foreign culture is presented in it.
23．When can you enjoy the oldest arts festival in the United States?
A.Saturdays in May. B．Saturdays in July.
C．Sundays in May. D．Sundays in July.
