下列各句中划线成语使用错误的一项是（  ）

已知平面内两个定点$A\left(-1,0\right),B\left(1,0\right)$，过动点$M$作直线$AB$的垂线，垂足为$N$.若${\left|MN\right|}^2=\overrightarrow{AN}·\overrightarrow{BN}$，则动点$M$的轨迹是（   ）

1. 有一组单项式：$a^2$，$-\frac{a^3}{2}$ ，$-\frac{a^4}{3}$ ，.........，请观察它们的构成规律，用你发现的规律写出第10个单项式：____ ．

阅读理解

Choose Your One-Day-Tours!

    Tour A - Bath &Stonehenge: including entrance fees to the ancient Roman bathrooms and Stonehenge -￡37 until 26 March and ￡39 thereafter.

    Visit the city with over 2,000 years of history and Bath Abbey, the Royal Crescent and the Costume Museum, Stonehenge is one of the world's most famous prehistoric monuments dating back over 5,000 years.

    Tour B - Oxford & Stratford  including entrance fees to the University St Mary's Church Tower and Anne Hathaway's -￡32 until 12 March and ￡36 thereafter.

    Oxford: Includes a guided tour of England's oldest university city and colleges. Look over the "city of dreaming spires(尖顶）"from St Mary's Church Tower. Stratford: Includes a guided tour exploring much of the Shakespeare wonder.

    Tour C - Windsor Castle &Hampton Court including entrance fees to Hampton Court Palace -￡34 until 11 March and ￡37 thereafter.

    Includes a guided tour of Windsor and Hampton Court, Henry VIII's favorite palace. Free time to visit Windsor Castle (entrance fees not included).With 500 years of history, Hampton Court was once the home of four Kings and one Queen. Now this former royal palace is open to the public as a major tourist attraction. Visit the palace and its various historic gardens, which include the famous maze (迷宫)where it is easy to get lost!

    Tour D -Cambridge including entrance fees to the Tower of Saint Mary the Great -￡33 until 18 March and ￡37 thereafter.

Includes a guided tour of Cambridge, the famous university town, and the gardens of the 18th century.

宇宙中最基本的天体是（　　）