1. 副詞節中の「主語 + be動詞」の省略
    a. Cherry trees are special not only when (thy are) in blossom, but when (thy are) covered with golden and red leaves.
    b. While (he is) listening to music in his room, he always has many cups of coffee.
    c. Though (we were) very tired, we went on practicing soccer until sunset.
  2. 文修飾副詞
    a. Clearly, the boys have been swimming in the river. Their hair is wet.
    cf. She explained her plan to us very clearly.
    b. Fortunately, that is almost always what happens.
    c. Strangely, her work is very popular only in foreign(domestic) countries.