Scientists identified a gene mutation for breast cancer and (later) subsequently developed a test to identify people who carry the gene mutation.  Many immigrants believed that leaving home and looking for work in the New World was their only (choice) option . The discovery of gold in the Western United States (encouraged) fueled immigration to California.  The idea of a new life in a new country was very (appealing) attractive to many immigrants.  Many people would like the government to (end; eliminate) abolish the income tax, but this is unlikely to happen.  A/ An (very large) colossal storm damaged the immigrant’s farm.   The (origin) source of political discontent is often economic.  Many countries (at first) initially welcomed immigrants because they needed workers.  The (continuous) persistent failure of national economic policies has forced many people to look for jobs in other countries.  The slaves who were brought to the New World (suffered) endured terrible treatment and many of them even died.  多重下拉选择题